Can you please let us know if you're using the Bayesian filter, and if so, what is the size of the db.dat and db.dat.prb files in the \SpamFilter\Corpus directory? The Bayesian filter is the one single filter that uses up more CPU and RAM than all the others, and we often suggest to disable it. Bayesian filters where "the thing" 4 or 5 years ago, but nowdays spammers have learned how to easily bypass them.

If this issue still occurs after having disabled it, could you please zip and email us SpamFilter's activity logfile (support at logsat dot com) so we can have a look? If the file is over 8MB in size please email us so we can provide you with an FTP site to upload it (or we can download it from anywhere you'd like to place it).