Download can not finish, CPU load is very very high

I use Eset 4.2 Security Suite and have a Problem. When i download a file with Firefox 3.5, the download can not finish and i have a very high CPU Usage from ekrn.exe. How can i make the Download finsh faster?

 

Make sure you don't have Document protection registerd in the system (it isn't by default as of v. 4.2 but if you reinstalled over an older version while preserving the settings it might be registered. In such case, the file would be scanned at least twice by both web access and document protection modules.
Another reason for the delay may be that the file is a large archive with a lot of files inside. Decompression of archives in general takes time, no matter whether it's an antivirus program or compression tools. If you mind the delay you can try setting a size limit for scanned objects in the web access protection setup. Files from large archives should then be scanned upon extraction from the archives.

 

also disable automatic scanning by FF
http://www.ghacks.net/2008/06/04/disable-automatic-virus-scanning-in-firefox-3/