Big Brother Windows. Thanks Microsoft.

For the last few months I’ve been getting really frustrated with my computer randomly running slower than it should, using 100% CPU usage in the Explorer.EXE process. Now this process is critical to the way Windows works, it being the taskbar at the bottom of the screen as well as the directory browser, so when it uses 100% CPU, suddenly things take a lot longer to work, or lock up and appear to stop running.

In the past when things have slowed down, I’ve either waited until CPU usage reduced to 0%, or in the event that it didn’t, have terminated the Explorer process and restarted it using Task Manager. Tonight however I decided to investigate what was happening, and by using the SysInternals Process Explorer, have discovered that the cause was Explorer opening this registry key: HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\
UserAssist\{75048700-EF1F-11D0-9888-006097DEACF9}\Count

Manually opening this key from regedit took about 15 seconds – Yes, that’s 15 seconds to open one registry location!!! – and while I didn’t count the exact number of items, I believe it contained hundreds of thousands of keys. No wonder the Explorer process was going slow when it kept opening this key!

This site here discusses this registry key: http://www.utdallas.edu/~jbs024000/articles/explorer_spy.html. Basically the guy has investigated what information is stored there and it includes things like websites visited, files accessed etc. ever since you installed Windows. Amazing stuff.

For me, the biggest issue was the performance hit rather than the privacy issue. I guess the registry has problems when more than a certain number of keys are stored in a single node, perhaps from fragmentation or just the sheer number of items, however I found that deleting the key immediately made Explorer.exe run at 0% CPU and it’s behaved perfectly ever since.

Quite why Microsoft decided to store all this information infinitely is beyond me, but if you are suffering from performance issues, or simply don’t like the Big Brother style logging system, then might want to consider tidying up your registry. I’ve not noticed any bad side effects, but be warned – editing your registry can have bad consequences, so delete keys at your own peril!

I’m looking forward to enjoying Windows working as it should do again – it was almost at the point of me reinstalling from scratch, but I feel I can put that off now until something else comes up! Enjoy.

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