Front end typing lag

I think I have figured this out. I turned off a number of Windows 7 "features" and typing became responsive. Here are the things I turned off:

Go to: Control Panel \ All Control Panel Items \ Programs and Features

Click Turn on/off Windows Features on left nav panel.

Turn off:

• Indexing Service
• Remote Differential Compression
• Windows Search

After doing this Mathematica is behaving normally. The basic problem seems to be that Mathematica is writing some file (or by side effect causing a file to be written) every time a character is typed, and the above "features" greatly slow down file access.