svchost.exe (Local Service) eating my RAM!

I have a vanilla Dell Vostro 270s with Intel i5 CPU, 8GB of RAM and Windows 7 Professional 64 bit. Add-ons are limited to IE10, Java, Flash, Zone Alarm Free Firewall, Microsoft Essentials A/V and Nero for DVD burning. I can also connect to a second (Windows XP) machine using remote desktop.

I thought this all worked well until I started experiencing massive slowdown which was corrected by rebooting. On investigation this is due to the RAM being used up over a period of about a week and the culprit is svchost.exe (Local Service). This instance of svchost.exe is associated with EventSystem, fdPHost, FontCache, netprofm, nsi, SstpSvc and WdiServiceHost. Beyond that I am stuck..

I believe others have had this sort of problem, but with variations, and I would appreciate any guidance as to what to do next.

While Java probably has nothing to do with the issue, you might want to uninstall Java and see if you ever miss it. Java presents a security risk.

Perhaps there was an update to Zone Alarm Free Firewall that is causing a problem. You might try uninstalling it - just as a test.

You might try this scan:
SFC /SCANNOW Command - System File Checker

Perhaps:
Troubleshoot Application Conflicts by Performing a Clean Startup
Hopefully, you can see the memory climb without having to wait a week.

Thanks Callender. It's all very confusing. The Dell Update Utility tells me that my desktop is up to date, Windows Update offers me an optional Intel graphics driver update but if I try and install that it fails with an error message stating that a later driver is already installed (!), but Intel own update utility offered me a much updated driver which (with fingers and toes crossed) I have now installed. Time will tell, but thanks anyway for the suggestion. I did make a Restore Point first...

That seems to have turned out well! Memory usage is now capped at under 3GB and svchost.exe (LocalService) has dropped way down the memory usage chart. I have also uninstalled Java as UNI's advice about it being unwanted these days is spot on. I just have 100MB+ of Intel Graphics bloatware cluttering up my hard disc...

It's very annoying that driver update info is so variable. I also have an AMD based HP ProBook which doesn't need a graphics update according to Windows, but does according to the ATI/Radeon utility. I guess I shall just have to bite the bullet and update that as well, but I just wish I understood why the update is required was doing as in this case there isn't a memory leak.

Many thanks to you both for your focussed and accurate advice.

After further testing I still have an svchost.exe (LocalService) memory leak but at a much lower rate, but one that increases exponentially with time (up to 2GB yesterday before I rebooted). I will try the further suggestions but don't want to apply a hotfix I don't need (!) so will tread carefully and feedback what I find.