It appears that having a regular expression starting with ".*" (and presumably other expressions that require backtracking?) causes a lockup when loading certain sites. The common denominator of these sites appears to be their use of TypeKit (a licensed CSS3 font-face solution).
Here's an example rule that causes problems for me:
.*fhqwhgads
Even if this is never matched on the page, I get a lockup. The following pattern, which is just as effective, causes no issues:
://.*fhqwhgads
I've adjusted my blocking rules to work around this issue.
Here's an example rule that causes problems for me:
.*fhqwhgads
Even if this is never matched on the page, I get a lockup. The following pattern, which is just as effective, causes no issues:
://.*fhqwhgads
I've adjusted my blocking rules to work around this issue.