2 possible reasons (as I have personally seen this problem);

Are you using any dialer apps (Tedds dialer tools, etc.)
Using a home replacement (Helix, launcher Pro)

I have found that these sometimes reproduce this problem

 

Noticed the same problem. Traced it down to Helix2. Replaced it with Helix1 and the problem went away.

In short, something is eating resources, which aren't available for the phone app.

 

I've been noticing this since i switched to Launcher Pro. I just download Autokiller from the Market and I will see if that helps.

 

when you run autokiller make sure to put LauncherPro in the excluded list. Also, I run launcherPro also and have this issue on some occasions. To me it is not a big deal because what is a few seconds.

 

thanks for the heads up! how do i do that exactly? lol

 

with ATK, and system monitor you just click on the application that is running and click exclude. Not sure how it would be done with autokiller...

 

ADW launcher does not have this problem as it does not eat cycles the way the others do, and it is not a memory hog.

 

Actually, this lag problem started when I added ADW launcher as the home screen.

 

If you are a rogers customer, disabling the Rogers 1 Contacts app fixes the issue.