Thanks Eric - EtreCheck results below.
Oddly enough I'd just downloaded and run it before I read your post... it suggested removing a couple of Safari adware extensions, which I did. I also ran Onyx and used it to clear caches etc.
Things seem better, though I haven't been using FCPX in the past couple of days...
EtreCheck version: 2.9.13 (267)
Report generated 2016-07-19 20:26:41
Download EtreCheck from https://etrecheck.com
Runtime 20:35
Performance: Poor
Click the [Support] links for help with non-Apple products.
Click the [Details] links for more information about that line.
Click the [Check files] link for help with unknown files.
Problem: Computer is too slow
Hardware Information: ⓘ
MacBook Pro (Retina, Mid 2012)
[Technical Specifications] - [User Guide] - [Warranty & Service]
MacBook Pro - model: MacBookPro10,1
1 2.3 GHz Intel Core i7 CPU: 4-core
8 GB RAM Not upgradeable
BANK 0/DIMM0
4 GB DDR3 1600 MHz ok
BANK 1/DIMM0
4 GB DDR3 1600 MHz ok
Bluetooth: Good - Handoff/Airdrop2 supported
Wireless: en0: 802.11 a/b/g/n
Battery: Health = Normal - Cycle count = 610
Video Information: ⓘ
Intel HD Graphics 4000
NVIDIA GeForce GT 650M - VRAM: 1024 MB
Color LCD 2880 x 1800
System Software: ⓘ
OS X Yosemite 10.10.5 (14F27) - Time since boot: less than an hour
Disk Information: ⓘ
APPLE SSD SM256E disk0 : (251 GB) (Solid State - TRIM: Yes)
EFI (disk0s1) <not mounted> : 210 MB
Recovery HD (disk0s3) <not mounted> [Recovery]: 650 MB
The Great Machine (disk1) / : 249.77 GB (34.09 GB free)
Core Storage: disk0s2 250.14 GB Online
USB Information: ⓘ
Apple Inc. FaceTime HD Camera (Built-in)
Apple Inc. BRCM20702 Hub
Apple Inc. Bluetooth USB Host Controller
Apple Inc. Apple Internal Keyboard / Trackpad
Thunderbolt Information: ⓘ
Apple Inc. thunderbolt_bus
Gatekeeper: ⓘ
Mac App Store and identified developers
Unknown Files: ⓘ
~/Library/LaunchAgents/com.fastestyoutub...plist
/Applications/Fastest Free YouTube Downloader.app/Contents/MacOS/FastestFreeYouTubeDownloader TrialExpired_OnComputerStartup
One unknown file found. [Check files]
Kernel Extensions: ⓘ
/Applications/EyeTV.app
[not loaded] com.elgato.driver.Pluto2 (1.1 - 2009-05-06) [Support]
/Applications/Private Eye.app
[loaded] com.radiosilenceapp.nke.PrivateEye (1.0 - SDK 10.7 - 2013-10-16) [Support]
/Library/Application Support/Blackmagic Design/Blackmagic DeckLink/Unsigned Extensions
[not loaded] com.blackmagic-design.desktopvideo.iokit.driver (10.6.8 - SDK 10.8 - 2016-06-06) [Support]
[not loaded] com.blackmagic-design.desktopvideo.multibridge.iokit.driver (10.6.8 - SDK 10.8 - 2016-06-06) [Support]
[not loaded] com.blackmagic-design.driver.BlackmagicIO (10.6.8 - SDK 10.8 - 2016-06-06) [Support]
[not loaded] com.blackmagic-design.driver.BlackmagicUsbIO (10.6.8 - SDK 10.8 - 2016-06-06) [Support]
/Library/Application Support/Blackmagic Design/Blackmagic DeckLink/Unsigned Extensions/DeckLink_Driver.kext/Contents/PlugIns
[not loaded] com.blackmagic-design.desktopvideo.firmware (10.6.8 - SDK 10.8 - 2016-06-06) [Support]
/Library/Extensions
[not loaded] com.sony.filesystems.pdudf (5.02.0d002 - SDK 10.6 - 2016-07-19) [Support]
[not loaded] com.sony.filesystems.pdudfr (5.02.0d002 - SDK 10.6 - 2016-07-19) [Support]
[loaded] com.sony.scsi.PDW-U1 (5.02.0d002 - SDK 10.6 - 2016-07-19) [Support]
/System/Library/Extensions
[loaded] com.Cycling74.driver.Soundflower (1.6.6 - SDK 10.6 - 2016-07-19) [Support]
[not loaded] com.LaCie.ScsiType00 (1.9.1 - SDK 10.5 - 2016-07-19) [Support]
[not loaded] com.matrox.vpg.AvcCodecDriver (4.2.0.0006 - SDK 10.7 - 2016-07-19) [Support]
[not loaded] com.matrox.vpg.BlackSwanDriver (4.2.0.0006 - SDK 10.7 - 2016-07-19) [Support]
[not loaded] com.matrox.vpg.ChartreuseGreenDriver (4.2.0.0006 - SDK 10.7 - 2016-07-19) [Support]
[not loaded] com.matrox.vpg.CoreAudioDriver (4.2.0.0006 - SDK 10.8 - 2016-07-19) [Support]
[not loaded] com.matrox.vpg.CoreMediaInputDriver (4.2.0.0006 - SDK 10.7 - 2016-07-19) [Support]
[not loaded] com.matrox.vpg.CoreMediaOutputDriver (4.2.0.0006 - SDK 10.7 - 2016-07-19) [Support]
[not loaded] com.matrox.vpg.EggWhiteDriverHelpers (1.0.0d1 - SDK 10.7 - 2016-07-19) [Support]
[not loaded] com.matrox.vpg.OutriggerOrangeDriver (4.2.0.0006 - SDK 10.7 - 2016-07-19) [Support]
[not loaded] com.matrox.vpg.RS422Driver (1.0.0d1 - SDK 10.7 - 2016-07-19) [Support]
[not loaded] com.matrox.vpg.RS422VirtualDriver (4.2.0.0006 - SDK 10.8 - 2016-07-19) [Support]
[not loaded] com.motu.driver.FireWireAudio (1.6 58373 - SDK 10.4 - 2016-07-19) [Support]
[not loaded] com.motu.driver.MicroBookAudio (1.6 58373 - SDK 10.4 - 2016-07-19) [Support]
[not loaded] com.motu.driver.PCIAudio (1.6 58373 - SDK 10.4 - 2016-07-19) [Support]
[not loaded] com.motu.driver.USBMidiKext (1.6 58373 - SDK 10.4 - 2016-07-19) [Support]
[not loaded] com.paceap.kext.pacesupport.master (5.9.1 - SDK 10.6 - 2016-07-19) [Support]
[not loaded] com.sony.driver.sxsexpressdrivers (2.0.0d007 - SDK 10.6 - 2016-07-19) [Support]
[not loaded] com.sony.driver.sxsus10drivers (2.0.0d007 - SDK 10.6 - 2016-07-19) [Support]
[not loaded] com.sony.driver.sxsxqddrivers (2.0.0d007 - SDK 10.6 - 2016-07-19) [Support]
[not loaded] com.sony.driver.sxsxqdexpressdrivers (2.0.0d007 - SDK 10.6 - 2016-07-19) [Support]
[not loaded] com.sony.filesystems.sxsudf_fs (2.0.0d007 - SDK 10.6 - 2016-07-19) [Support]
/System/Library/Extensions/PACESupportFamily.kext/Contents/PlugIns
[not loaded] com.paceap.kext.pacesupport.leopard (5.9.1 - SDK 10.4 - 2013-02-01) [Support]
[not loaded] com.paceap.kext.pacesupport.panther (5.9.1 - SDK 10.-1 - 2013-02-01) [Support]
[loaded] com.paceap.kext.pacesupport.snowleopard (5.9.1 - SDK 10.6 - 2013-02-01) [Support]
[not loaded] com.paceap.kext.pacesupport.tiger (5.9.1 - SDK 10.4 - 2013-02-01) [Support]
System Launch Agents: ⓘ
[not loaded] 6 Apple tasks
[loaded] 141 Apple tasks
[running] 64 Apple tasks
System Launch Daemons: ⓘ
[not loaded] 42 Apple tasks
[loaded] 139 Apple tasks
[running] 82 Apple tasks
Launch Agents: ⓘ
[not loaded] com.adobe.AAM.Updater-1.0.plist (2015-11-27) [Support]
[running] com.adobe.AdobeCreativeCloud.plist (2015-10-28) [Support]
[running] com.avid.ApplicationManager.plist (2016-04-29) [Support]
[running] com.avid.ApplicationManagerHelper.plist (2015-09-22) [Support]
[running] com.blackmagic-design.DesktopVideoFirmwareUpdater.plist (2016-06-06) [Support]
[loaded] com.google.keystone.agent.plist (2016-07-11) [Support]
[loaded] com.intego.backupassistant.agent.plist (2014-07-30) [Support]
[loaded] com.lacie.LaCieDesktopManagerAgent.plist (2016-07-19) [Support]
[running] com.matrox.vpg.Agent.plist (2014-06-05) [Support]
[loaded] com.matrox.vpg.MaxAgent.plist (2014-06-05) [Support]
[running] com.motu.MOTULauncher.plist (2010-12-18) [Support]
[not loaded] com.oracle.java.Java-Updater.plist [Support]
[running] org.chromium.chromoting.plist (2016-06-21) [Support]
Launch Daemons: ⓘ
[loaded] PACESupport.plist (2013-02-01) [Support]
[loaded] com.adobe.agsservice.plist (2015-10-28) [Support]
[loaded] com.adobe.fpsaud.plist (2016-06-29) [Support]
[running] com.avid.asset.cache.service.plist (2015-11-20) [Support]
[running] com.avid.asset.delivery.service.plist (2015-11-20) [Support]
[loaded] com.avid.bsd.shoetoolv120.plist (2016-05-24) [Support]
[running] com.avid.project.sync.service.plist (2015-11-20) [Support]
[running] com.avid.transport.client.plist (2015-11-20) [Support]
[running] com.blackmagic-design.DesktopVideoHelper.plist (2016-06-06) [Support]
[loaded] com.blackmagic-design.desktopvideo.XPCService.plist (2016-06-06) [Support]
[running] com.blackmagic-design.streaming.BMDStreamingServer.plist (2016-06-06) [Support]
[loaded] com.bombich.ccc.plist (2015-01-14) [Support]
[running] com.crashplan.engine.plist (2016-07-13) [Support]
[loaded] com.google.keystone.daemon.plist (2016-07-11) [Support]
[running] com.intego.BackupAssistant.daemon.plist (2014-07-30) [Support]
[loaded] com.lacie.LaCieDesktopManagerDaemon.plist (2015-08-12) [Support]
[loaded] com.microsoft.office.licensing.helper.plist (2010-08-25) [Support]
[not loaded] com.oracle.java.Helper-Tool.plist [Support]
[running] com.paceap.eden.licensed.plist (2015-08-10) [Support]
[loaded] com.radiosilenceapp.nke.PrivateEye.plist (2011-10-06) [Support]
[loaded] com.stclairsoft.Jettison.DriverHelper.plist (2015-06-03) [Support]
[loaded] com.transcend.TSRecoverHandlerHelp.plist (2015-11-17) [Support]
[running] com.transcend.TSSleepHandlerHelp.plist (2015-11-17) [Support]
[loaded] com.transcend.TSTRIMHandlerHelp.plist (2015-11-17) [Support]
[loaded] com.tunabellysoftware.TGFanHelper.plist (2015-07-09) [Support]
User Launch Agents: ⓘ
[failed] com.fastestyoutubedownloader.TrialExpired.GoldFreeFirstWeek.plist (2014-04-11) [Support]
[failed] com.google.keystone.agent.plist (2013-07-22) [Support]
User Login Items: ⓘ
macfusionAgent Application (/Applications/Macfusion.app/Contents/Resources/macfusionAgent.app)
Arq Agent Application (/Applications/Arq.app/Contents/Library/LoginItems/Arq Agent.app)
Jettison Application (/Applications/Jettison.app)
iTunesHelper Application (/Applications/iTunes.app/Contents/MacOS/iTunesHelper.app)
uTorrent Application (/Applications/uTorrent.app)
Dropbox Application (/Applications/Dropbox.app)
BOINCManager Application Hidden (/Applications/BOINCManager.app)
XDCAM Drive Monitor Application (/Applications/XDCAM Drive/XDCAM Drive Monitor.app)
CrashPlan menu bar Application (/Applications/CrashPlan.app/Contents/Helpers/CrashPlan menu bar.app)
XDMSetupHelper Application (/Library/Application Support/XDCAM Drive/Helpers/XDMSetupHelper.app)
Other Apps: ⓘ
[running] com.adobe.acc.AdobeDesktopService.126696.05592340-A9CA-4100-884D-76D2AD25A0FC
[running] com.adobe.accmac.76712
[running] com.code42.b42menuextra.109088
[running] com.etresoft.EtreCheck.133512
[loaded] com.fiplab.BatteryHealthHelper
[running] com.fiplab.batteryhealth.21616
[running] com.getdropbox.dropbox.32124
[running] com.google.Chrome.8552
[running] com.haystacksoftware.ArqAgent.18776
[running] com.sony.vfam.monitor.85800
[running] com.stclairsoft.Jettison.43200
[running] jp.co.canon.cijscannerregister.5144
[running] org.mgorbach.macfusion2.macfusionAgent.109372
[loaded] 374 Apple tasks
[running] 192 Apple tasks
Internet Plug-ins: ⓘ
JavaAppletPlugin: 15.0.0 - SDK 10.7 (2015-03-31) Check version
FlashPlayer-10.6: 22.0.0.209 - SDK 10.9 (2016-07-18) [Support]
AdobeAAMDetect: 3.0.0.0 - SDK 10.9 (2015-11-27) [Support]
Flash Player: 22.0.0.209 - SDK 10.9 (2016-07-18) [Support]
Default Browser: 600 - SDK 10.10 (2016-01-03)
QuickTime Plugin: 7.7.3 (2016-01-03)
SharePointBrowserPlugin: 14.0.0 (2010-08-25) [Support]
nplastpass: 2.5.5 (2014-04-28) [Support]
Silverlight: 5.1.30317.0 - SDK 10.6 (2014-05-14) [Support]
iPhotoPhotocast: 7.0 (2013-08-30)
User internet Plug-ins: ⓘ
Aspera Web 3.6.1.111259: Unknown - SDK 10.9 (2015-09-11) [Support]
Google Earth Web Plug-in: 7.1 (2013-10-07) [Support]
Safari Extensions: ⓘ
LastPass - LastPass - https://lastpass.com (2016-07-16)
3rd Party Preference Panes: ⓘ
Blackmagic Desktop Video (2016-06-06) [Support]
remoting_host_prefpane (2016-07-13) [Support]
Flash Player (2016-06-29) [Support]
Growl (2013-07-20) [Support]
Matrox CompressHD (2014-06-05) [Support]
Matrox Utilities (2014-11-10) [Support]
XDCAM Drive Monitor (2015-10-16) [Support]
Time Machine: ⓘ
Skip System Files: NO
Mobile backups: ON
Auto backup: YES
Volumes being backed up:
The Great Machine: Disk size: 249.77 GB Disk used: 215.67 GB
Destinations:
Data [Network]
Total size: 2.00 TB
Total number of backups: 85
Oldest backup: 14/07/2015 21:58
Last backup: 19/07/2016 14:52
Size of backup disk: Excellent
Backup size 2.00 TB > (Disk size 249.77 GB X 3)
Top Processes by CPU: ⓘ
566% kernel_task
47% Finder
18% com.apple.WebKit.WebContent
15% App Store
14% WindowServer
Top Processes by Memory: ⓘ
760 MB kernel_task
500 MB Google Chrome Helper(5)
369 MB Dock
328 MB AvidAppManHelper
303 MB Finder
Virtual Memory Information: ⓘ
20 MB Free RAM
7.97 GB Used RAM (1.35 GB Cached)
0 B Swap Used
Diagnostics Information: ⓘ
Jul 19, 2016, 07:37:24 PM /Library/Logs/DiagnosticReports/CheckVersion_2016-07-19-193724_[redacted].crash
/Library/Application Support/Blackmagic Design/*/CheckVersion.app/Contents/MacOS/CheckVersion
Jul 19, 2016, 07:34:31 PM Self test - passed
Jul 19, 2016, 07:17:56 PM /Library/Logs/DiagnosticReports/CheckVersion_2016-07-19-191756_[redacted].crash
Jul 19, 2016, 07:10:13 PM /Library/Logs/DiagnosticReports/CheckVersion_2016-07-19-191013_[redacted].crash
Jul 19, 2016, 06:46:44 PM /Library/Logs/DiagnosticReports/Google Chrome_2016-07-19-184644_[redacted].hang
/Applications/Google Chrome.app/Contents/MacOS/Google Chrome
Jul 19, 2016, 06:41:16 PM /Library/Logs/DiagnosticReports/CheckVersion_2016-07-19-184116_[redacted].crash
Jul 19, 2016, 04:20:25 PM /Library/Logs/DiagnosticReports/Finder_2016-07-19-162025_[redacted].cpu_resourc e.diag [Details]
/System/Library/CoreServices/Finder.app/Contents/MacOS/Finder
Jul 18, 2016, 11:07:27 PM /Library/Logs/DiagnosticReports/nsurlstoraged_2016-07-18-230727_[redacted].cpu_ resource.diag [Details]
/usr/libexec/nsurlstoraged
Jul 18, 2016, 10:11:03 PM /Library/Logs/DiagnosticReports/com.apple.WebKit.WebContent_2016-07-18-221103_[ redacted].cpu_resource.diag [Details]
/System/Library/Frameworks/WebKit.framework/Versions/A/XPCServices/com.apple.We bKit.WebContent.xpc/Contents/MacOS/com.apple.WebKit.WebContent
Jul 18, 2016, 03:42:21 PM /Library/Logs/DiagnosticReports/nsurlstoraged_2016-07-18-154221_[redacted].cpu_ resource.diag [Details]
Jul 18, 2016, 01:49:39 PM /Library/Logs/DiagnosticReports/CheckVersion_2016-07-18-134939_[redacted].crash
Jul 18, 2016, 12:25:45 AM /Library/Logs/DiagnosticReports/mds_stores_2016-07-18-002545_[redacted].crash
/System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/Metadat a.framework/Versions/A/Support/mds_stores
Jul 18, 2016, 12:14:31 AM /Library/Logs/DiagnosticReports/CheckVersion_2016-07-18-001431_[redacted].crash
Jul 17, 2016, 08:47:01 PM /Library/Logs/DiagnosticReports/nsurlstoraged_2016-07-17-204701_[redacted].cpu_ resource.diag [Details]
Jul 17, 2016, 03:12:12 PM ~/Library/Logs/DiagnosticReports/XDCAM Drive Monitor_2016-07-17-151212_[redacted].crash
com.sony.vfam.monitor - /Applications/XDCAM Drive/XDCAM Drive Monitor.app/Contents/MacOS/XDCAM Drive Monitor
Jun 30, 2016, 08:56:31 PM /Library/Logs/DiagnosticReports/Kernel_2016-06-30-205631_[redacted].panic [Details]