Thanks LLLaass. I've just done the etrecheck as I couldn't run the AHT (I've no disks)
here it is:
EtreCheck version: 3.0.3 (307)
Report generated 2016-09-06 19:55:09
Download EtreCheck from https://etrecheck.com
Runtime 3:08
Performance: Good
Click the [Support] links for help with non-Apple products.
Click the [Details] links for more information about that line.
Problem: Beachballing
Hardware Information: ⓘ
Mac mini (Mid 2010)
[Technical Specifications] - [User Guide] - [Warranty & Service]
Mac mini - model: Macmini4,1
1 2.4 GHz Intel Core 2 Duo CPU: 2-core
8 GB RAM Upgradeable - [Instructions]
BANK 0/DIMM0
4 GB DDR3 1067 MHz ok
BANK 1/DIMM0
4 GB DDR3 1067 MHz ok
Bluetooth: Old - Handoff/Airdrop2 not supported
Wireless: en1: 802.11 a/b/g/n
Video Information: ⓘ
NVIDIA GeForce 320M - VRAM: 256 MB
e2752Vq 1920 x 1080
System Software: ⓘ
OS X El Capitan 10.11.6 (15G31) - Time since boot: about 5 hours
Disk Information: ⓘ
Hitachi HTS545050B9SA02 disk0 : (500.11 GB) (Rotational)
EFI (disk0s1) <not mounted> : 210 MB
Macintosh HD (disk0s2) / : 499.25 GB (381.83 GB free)
Recovery HD (disk0s3) <not mounted> [Recovery]: 650 MB
HL-DT-STDVDRW GA32N ()
USB Information: ⓘ
Apple Inc. BRCM2070 Hub
Apple Inc. Bluetooth USB Host Controller
Apple Computer, Inc. IR Receiver
Gatekeeper: ⓘ
Mac App Store and identified developers
System Launch Agents: ⓘ
[not loaded] 8 Apple tasks
[loaded] 161 Apple tasks
[running] 69 Apple tasks
System Launch Daemons: ⓘ
[not loaded] 46 Apple tasks
[loaded] 163 Apple tasks
[running] 81 Apple tasks
User Login Items: ⓘ
iTunesHelper Application (/Applications/iTunes.app/Contents/MacOS/iTunesHelper.app)
Internet Plug-ins: ⓘ
Default Browser: 601 - SDK 10.11 (2016-09-23)
QuickTime Plugin: 7.7.3 (2016-09-23)
JavaAppletPlugin: 15.0.1 - SDK 10.7 (2016-07-22) Check version
3rd Party Preference Panes: ⓘ
None
Time Machine: ⓘ
Skip System Files: NO
Auto backup: YES
Volumes being backed up:
Macintosh HD: Disk size: 499.25 GB Disk used: 117.42 GB
Destinations:
Untitled [Local]
Total size: 2.00 TB
Total number of backups: 24
Oldest backup: 11/06/2016, 21:31
Last backup: 04/09/2016, 22:34
Size of backup disk: Excellent
Backup size 2.00 TB > (Disk size 499.25 GB X 3)
Top Processes by CPU: ⓘ
53% firefox
8% kernel_task
1% fontd
1% WindowServer
0% askpermissiond
Top Processes by Memory: ⓘ
1.10 GB firefox
714 MB kernel_task
131 MB mds_stores
131 MB mdworker(8)
123 MB WindowServer
Virtual Memory Information: ⓘ
3.34 GB Free RAM
4.91 GB Used RAM (1.47 GB Cached)
0 B Swap Used
Diagnostics Information: ⓘ
Sep 23, 2016, 09:53:03 PM ~/Library/Logs/DiagnosticReports/suggestd_2016-09-23-215303_[redacted].crash
/System/Library/PrivateFrameworks/CoreSuggestions.framework/Versions/A/Support/ suggestd
Sep 23, 2016, 09:34:19 PM /Library/Logs/DiagnosticReports/coreduetd_2016-09-23-213419_[redacted].cpu_reso urce.diag [Details]
/usr/libexec/coreduetd
Sep 23, 2016, 09:23:24 PM /Library/Logs/DiagnosticReports/Safari_2016-09-23-212324_[redacted].hang
/Applications/Safari.app/Contents/MacOS/Safari
Sep 6, 2016, 07:52:38 PM ~/Library/Logs/DiagnosticReports/system_profiler_2016-09-06-195238_[redacted].c rash
/usr/sbin/system_profiler
Sep 6, 2016, 02:40:31 PM Self test - passed
Sep 4, 2016, 09:06:24 PM /Library/Logs/DiagnosticReports/VTEncoderXPCService_2016-09-04-210624_[redacted ].cpu_resource.diag [Details]
/System/Library/Frameworks/VideoToolbox.framework/Versions/A/XPCServices/VTEnco derXPCService.xpc/Contents/MacOS/VTEncoderXPCService
Sep 4, 2016, 08:59:20 PM ~/Library/Logs/DiagnosticReports/Photos_2016-09-04-205920_[redacted].crash
/Applications/Photos.app/Contents/MacOS/Photos