WSE3 AuthenticateToken gets called on every web service call

WSE3 AuthenticateToken gets called on every web service call

I have microsoft asp.net web services that use WSE3. They use a
SecurityToken for security (Microsoft.Web.Services3.Security.Tokens
namespace).
The AuthenticateToken method gets called every single time a web service
method gets called by the client. The problem is, it speaks to the
database, which causes a major performance problem. I don't need to call
it on every web service call, so is there any way to cache the token so it
doesn't call AuthenticateToken as often? Or any other way of preventing
the AuthenticateToken method being called and just assuming the web
service call is valid?
Thanks