downloads causing heavy PC lag

You need to sort the ask List by CPU %. Your CPU is peg at 100% and we cannot see which tasks are the culprit.

^^ Yes running ESET Nod32 AntiVirus

Hi guys! This is my first post on this forum and I do it in order to rescue you MrCharles

I had exactly the same problem than you. It happens that sometimes my system runs lower than usualy even if I found a cure.
I have chosen Eset Nod32 and I have 2GB of RAM too so I know how your system is used to run (however I have a c2d but it doesn not care)
The problem is that Seven, in all of its versions, seems to have some difficulties managing less than 2GB of RAM. Seven is actually made to run with the very half of all the RAM you have in your PC (if you have 2GB it will need about 1GB to run properly).
Nevertheless Win7 has the capacity to unlock exactly what it needs to run, I mean RAM. So when you dl like I do with Mozilla Firefox or Flashget or I-dont-know-what the more you write on your HDD, the more your dl-manager will need some RAM to run and when there is no available RAM anymore, the soft (firefox) stops everything it was doing and try to find the ressources to continue downloading.
It is kind of irritating when you were about to put an end to a 10GB download that took 5h! Hopefully, as I said, Win7 may close programs or processes in order to decrease the quantity of RAM in use and sometimes it happens that firefox reloads and continues downloading but often it does not. So the cure I found is very simple, you have to use a download manager that may stop downloading while you are rebooting your system and restarts after you made it. Of course there is another solution: get more RAM
My system was using about 45% out of 2GB RAM when I started downloading, 2h later it uses more than 95% and my HDD makes some unusual noises making Win7 running very very slowly but now I make breaks every 2h and reboot windows (in the wait of my second pin of 2GB ^^)!

Unfortunately Win7 has been built like that and people like us (with less than 4GB of RAM) pay the price...

So in conclusion theres no way to fix this

MrCharles,
the snapshot shows 2 striking things:
1) Firefox is consuming 32 % cpu resources. Thats abnormal to say the least. Would suggest you uninstall and try using a different browser. Or at least uninstall, clean up, then reinstall firefox.
2) The other is the that ntkernel and system cpu usage. Suggest you scan for malware with malwarebytes Antimalware. Also suggest you turn off indexing on all drives.

I did not try Chrome, maybe it needs less RAM than Firefox but i am not sure at all.
I have installed Malwarebytes' and turn the environmental protection on (in order to instantly detect malwares) then my system does not run faster..
I heard there was a way to defrag the RAM, it will be useful, perhaps you should try.

MrCharles said:

This is the strangest problem I've come across with Windows 7. once I start downloading files, or my browser starts downloading images/streaming videos my entire PC lags until the downloads are complete or have been paused. Then my computer runs fine again.

Are you using a virus scanner that checks downloads?

If it's hogging system resources (and many do) it could be simply that the virus scanner is pounding your CPU trying to make sure your system doesn't get messed up by downloads.... Ummm, wait a second, what's wrong with that picture???

MrCharles, are you running Malwarebytes anti malware, if so disable the system ip protection

My issues are now resolved and i can download at full speed, transfer across the network with absolutely no lag