Game runs fine but lags other programs

Hello so the game that I am having trouble with is called fly for fun. While playing this game in window mode 1280x1024. I can get into the game fine and play with 60fps or higher as you can see the specs for this game arent high

System Minimum System Recommended System
CPU PentiumIII 800MHZ PentiumIII 1GHz
RAM 128MB 512MB
VGA Geforce 2mx 200 32mb-64mb Geforce 3 128mb-256mb

When I am playing and lets say I alt tab out programs like firefox will take longer to open a new tab and stuff like that. Also lets say I try to go to my computer or any other folder it take up to 30seconds to open the folder. But when I play this game in fullscreen everything works fine except that when I am typing outside of the game it goes slow. So my question is why is the game slowing down my other programs? The game runs fine without any problems.
My specs are
AMD Athlon(tm) 64 Processor 3500+
NVIDIA GeForce 8600 GT XXX
1.5 GB

If you need any other information please ask thanks for reading this.

 

Also when I go to the task manager and have the game open it isnt in the list with the processes.

 

It's just because you are running a game. It's understandably is going to soak up some computer cycles when it's open. Games are supposed to be the only thing running and honestly, I think thats pretty common. My computer is just about comparable to that, but when I run a game from 1995, my itunes glitches and skips when it tries to play. I think that's just reality in this case.

 

If you want heavy multitasking ability, you need a multi-core CPU.