network access with WPA much slower than with plain WEP128?

Hi, i switched from WEP to WPA for security reasons, and now it seems that data transfers over my wlan (54mbit) is MUCH slower than before... could that be possible? laptop in question is not that powerful (p3 700mhz). bye, MH -- gpg key fingerprint: 5F64 4C92 9B77 DE37 D184 C5F9 B013 44E7 27BD 763C