KMail slows system down

Hi, are you experiencing the same problem that with about 20 mailing lists KMail slows the system down regularly? Especially when you set the maximum time messages are kept in a folder is set to say 30 days? It's a fact that I suffer great performance problems with my about 20 mailing lists, not speaking about turning on the included anti-spam filter mechanism using spamassassin (and bogofilter), which really pisses me off. I am thinking about changing to another mail client, once again. But exept for text-based MUAs, which one could be faster? Thunderbird...? Doubt that. Greetings, -Ré -- Registered Linux User #324404