Does WPA2 security cause wireless internet connection to slow down?

[sastusbulbas]

Hi,

I have my wireless router connected with WPA2 settings, with wireless it reports excellent connection, but internet connection is painfully slow, If I connect a cable to the router internet browsing is faster.

I only have a 20mb broadband connection, and chose my Asus WL-500G due to its USB ports, and thought 54MBps would be enough anyway.

Is the WPA security known to slow down internet speed, any opinion on what to look at to get better internet speed?