I recently got a new Thinkpad T60 notebook. It has an Intel core duo T2600 @2.16GHZ. When BOINC is running my applications stop/freeze for a period of time then continue. BOINC shows 2 WU's running on the 2 processors (setup as 2 processors in preferences). For example, opening a Microsoft Excel spreadsheet takes several minutes to open with boinc running. Only 15 seconds without BOINC.

Has anyone else seen this happen?

Overheating and CPU throttling? And in my optinion, 15 seconds is still too much to open a spreadsheet

Maybe its using up too much swap space?

I also have a laptop with a T2250 Core Duo (1.73 GHz) with 1.5 GB of memory, but I don't experience any type of slowdown when running BOINC.

I have 2 gb memory. Task manager shows 1gb available.

I went an installed 5.6.5 development version. it is better but not still impactful.

What projects are you running? Also, if the benchmarks start up, that will slow down your comp, but that would only take a min or 2 and only happen once every 2 weeks or so.