I just updated to r371 and it looked like the X10 system was kinda slow again. I checked the logs and am not seeing the X10 time stamps with the I/O statements, so I was thinking perhaps this was an old version of the XTenLib.dll? I'm going to try the one you posted last, but was just posting in case something unintentional went backwards.
Also, I found a strange occurrence that I cannot duplicate. I have my test script enabled and no other X10 related programs enabled. I selected the toggle button on the switch module in HG which should have toggled the light as well. It did, but it also sent an unrelated command. I couldn't figure out where it did this or why and it wasn't in the logs so I don't know what happened. Basically, I toggled B6 (switch) in HG and A6 (light) turned on but B1 (chime module) also triggered. I checked my AHP log and it didn't show nor did my XTBM. If this recurs and I can trap the source, I'll let you know if it's my side or HG.