Thanks, I was able to reproduce the issue. The cause appears to be a stack overflow in PCRE. I notice that if the following line is commented out the issue does not occur:
;%feedconverted = $regsubex(%feedconverted,/<img(\s|\S|=|\")* alt=\"(\s|\S)\"(\s|\S|=|\")*( \/)?>/g,\2)
Is it possible that the issue is due to a problem with the above expression?