iMac running slow with Mountain Lion

My 2007 iMac (4GB RAM) has Mountain Lion loaded (10.8.4).

Since loading its running very slow - 20-30 sec to login, more than 20 sec to open Firefox, etc.

Before I loaded ML I was told the system specs were adequate but i am wondering if I should go back to Snow Leopard.

Below some info on my system (having read a previous post on a related subject). I looked in Console and noticed a line repeating. I used to have a Lexmark printer a few months back, but removed that some time back (and also have had a new hard drive installed since and done a reinstall).

2013/08/30 8:55:47,756 PM com.apple.launchd.peruser.502[2228]: (com.lexmark.bmlaunchd[2636]) Exited with code: 1
2013/08/30 8:55:47,756 PM com.apple.launchd.peruser.502[2228]: (com.lexmark.bmlaunchd) Throttling respawn: Will start in 10 seconds

Hardware Information:

iMac (20-inch, Mid 2007)

iMac - model: iMac7,1

1 2.4 GHz Intel Core 2 Duo CPU: 2 cores

4 GB RAM

Video Information:

ATI,RadeonHD2600 - VRAM: 256 MB

System Software:

OS X 10.8.4 (12E55) - Uptime: 0 days 22:14:14

Disk Information:

WDC WD5000AAKX-00ERMA0 disk0 : (500.11 GB)

disk0s1 (disk0s1) <not mounted>: 209.7 MB

Macintosh HD (disk0s2) /: 499.25 GB (408.55 GB free)

Recovery HD (disk0s3) <not mounted>: 650 MB

USB Information:

Apple Inc. Built-in iSight

Apple, Inc. Keyboard Hub

Apple Inc. Apple Keyboard

Apple Inc. Bluetooth USB Host Controller

Apple Computer, Inc. IR Receiver

FireWire Information:

Thunderbolt Information:

Kernel Extensions:

Problem System Launch Daemons:

Problem System Launch Agents:

[failed] com.apple.accountsd.plist

[failed] com.apple.coreservices.appleid.authentication.plist

[failed] com.apple.pbs.plist

[failed] com.apple.printtool.agent.plist

Launch Daemons:

[failed] com.adobe.fpsaud.plist

[loaded] com.google.keystone.daemon.plist

[loaded] com.microsoft.office.licensing.helper.plist

[loaded] com.trusteer.rooks.rooksd.plist

[loaded] com.wdc.drivemanagerservice.plist

Launch Agents:

[loaded] com.google.keystone.agent.plist

[loaded] com.hp.messagecenter.launcher.plist

[failed] com.lexmark.bmlaunchd.plist

[failed] com.lexmark.lexnetlaunchd.plist

[loaded] com.trusteer.rapport.rapportd.plist

User Launch Agents:

[loaded] com.adobe.ARM.202f4087f2bbde52e3ac2df389f53a4f123223c9cc56a8fd83a6f7ae.plist

User Login Items:

iTunesHelper

AirPort Base Station Agent

Google Drive

Pinelands High School

CNQL1213_ButtonManager

ConnectService

WDDriveManagerStatusMenu

3rd Party Preference Panes:

Flash Player

Flip4Mac WMV

Rapport

Internet Plug-ins:

AdobePDFViewer.plugin

AdobePDFViewerNPAPI.plugin

DirectorShockwave.plugin

Flash Player.plugin

FlashPlayer-10.6.plugin

Flip4Mac WMV Plugin.plugin

Google Earth Web Plug-in.plugin

googletalkbrowserplugin.plugin

iPhotoPhotocast.plugin

JavaAppletPlugin.plugin

npgtpo3dautoplugin.plugin

o1dbrowserplugin.plugin

OfficeLiveBrowserPlugin.plugin

QuickTime Plugin.plugin

SharePointBrowserPlugin.plugin

Silverlight.plugin

User Internet Plug-ins:

Bad Fonts:

None

Top Processes by CPU:

77% parentalcontrolsd

72% socketfilterfw

23% securityd

8% activitymonitord

6% Console

2% firefox

2% Shell

2% WindowServer

1% EtreCheck

0% Activity Monitor

Top Processes by Memory:

229 MB
socketfilterfw

217 MB
firefox

121 MB
parentalcontrolsd

102 MB
mds

66 MB Finder

61 MB WindowServer

57 MB Dock

49 MB Shell

45 MB rapportd

43 MB securityd

Virtual Memory Statistics

1.25 GB
Free RAM

1.86 GB
Active RAM

429 MB
Inactive RAM

487 MB
Wired RAM

9.02 GB
Page-ins

0 B Page-outs