[Dovecot] sieve filtering setup

I'm looking at implementing sieve in my environment. Software is: dovecot-1.2-sieve revision 1022:3c9a22c28156 dovecot-1.2 revision 9269:a303bb82c1c9 AIX 5.3 with sendmail mta using prescribed deliver lda.

I have a few questions. I'll have 110k sieve files(1 for each user).
Does sieve read the file each time a new message is accepted by
sendmail? Are there any measurements on cpu load for sieve filters?

Thanks, Jonathan