I was pretty sure I was doing the exact same search, but I verified this morning and actually got some informal timings. I'm doing the search in a very large GoG. I ran the search 5 times in succession to assure the Windows file cache was fully primed and timed the 5th run. I took the timings in 6.00 first, then in 6.01B6, and then just for grins went back to 6.00. Here are the results:
6.00 - 4 seconds
6.01B6 - 57 seconds
6.00 - 4 seconds
My machine is pretty whimpy by modern standards (2.4GHz Core 2 Duo, only 3G RAM), but it seems like something must have changed in 6.01B6 to cause such a dramatic change in search performance with all other things being equal. I forgot to mention I am using Windows 7 x64 and using the 64-bit versions of Newsbin (although I can't imagine that makes any difference).
On a hunch I suspected maybe the problem with 6.01B6 is that it is always searching all groups regardless of which GoG is actually being filtered on. So I ran with some smaller GoGs selected and they ran much quicker which seems to indicate this is not the problem.
Thanks for looking into this Quade. I guess since you can't recreate it and no one else seems to be having the same problem, it must be some quirk of my system. It's a good excuse for me to get a new system!