My PC slows down when trying to download

[mamus]

Hi there, first post here and i need a little help, i've been using bitcomet for some years already and never had a problem like this one.

Whenever i try to download a file that's 13+ GB my computer slows down a lot and the cpu gets to 30-100% usage, can still navigate but with a lot of lag.

I have already downloaded many times larger files, so i really don't have a clue what may be happening, i believe it also slows down a bit my download speed.

I'm using BitComet v. 1.37 64bit o Windows 7

I've also tried downloading the portable 1.37 version it gets a little better letting me navigate normally in my computer but still when i try to open bitcomet it lags a lot and i have no other choice than shut down the process.

I have not tried another version though

ADSL Modem but haven't done port forwarding since it has never slowed down my downloading speed.

I use ESET Smart Security 7.0.302.26

10mb Download speed

1mb upload speed

My computer:

Core 2 Duo @ 2.4Ghz

4GB RAM

Many Thanks

Ps. Sorry for my english, and long post, trying to make it as clear as possible!

[The UnUsual Suspect]

is it just your browsing that is effected or are other non-internet apps slow too?

[mamus]

Now it seems to be working fine, however the program itself lags a lot when i click anywhere in the program window. I mean, only bitcomet seems affected by the lag (using portable version)

So it is pretty annoying because when i want to start downloading it lags a lot however it starts downloading after a while, but can't touch anything in the window or even stop the download because it will state "not responding" and the only way to fix it is to kill the task.

Can it be because there are too many files in the torrent?

thanks!