I was having the same problem, although not as bad or processor intensive as the other posts suggest. I am using a Vaio Laptop running Windows XP (Final Service Pack). In my case, the error messages only came up if I accessed, 'Reset Safari' or 'Preferences > Security or Privacy'.
The error message always was:
"11d8: Webkit2WebProcess.exe - unable to locate component
This application has failed to start because xpcom.dll was not found"
Once you have okayed this, Safari 5.1 ran without any problems, although there were behavioural anomalies that were not there in previous versions of Safari. For example I experienced so many bugs when using Gmail, and processes would suddenly use so much CPU that it was so irritating to do anything. I had to wait till it all calmed down to even launch a software.
In this particular computer, ‘xpcom.dll’ is a component of OpenOffice Suite and lives in OpenOffice Programme Folder. It is a software created by Mozilla Partnership. In my case or in the case of anyone running Windows XP and have OpenOffice installed, the problem is to do with ‘Webkit2WebProcess.exe’ not knowing where ‘xpcom.dll’ is.
Safari does not give an option to add or look for a component, so unless you go through a potentially dangerous, Windows directory edit, there isn’t much anyone can do him or herself.
In my searches, I also read that ‘Webkit2WebProcess.exe’ has been written using Microsoft Visual C ++ Code. In my case, I uninstalled all MS Visual C components a while ago, but some patches and updates of this still remains in my system, and even if you remove everything, the next Windows Update will add the patches again for stability. Microsoft Visual C is an optional Windows Update for Windows XP, and some XP users may not have installed this at all, and therefore, may not experience these problems. Similarly, those do not have OpenOffice on Windows XP may not experience this error. However, those who run Safari on Windows Vista or 7 may have much more intensive problems including Safari crashes.
I repeatedly sent bug reports to Apple using Safari Help Menu. The one I sent last night was quite strongly worded. Today, it took longer than usual to launch Safari, and the error message has now gone!
So, I recommend to all of you to send bug reports to Apple, using Safari Help Menu. You don’t need to include screenshots or source code of the current page when you do this, but explain your problem clearly with the contents of the error messages you get.
Safari, in my opinion is the simplest and most elegant browser available. So, I think we should stick to it until Apple solves this problem in an update.
Good luck.
