wpc54g-2 card extremely slow

I see this topic is somewhat redundant, but I was unable to find any
posts that answers the problem.

Out of nowhere, my wireless speed is extremely slow. I connect to a
router that I do not have access to (with permission of course) which
is a DLink router. I am unsure what model but I had no problems at all
with my connection. I show 54 Mbps on my connection but a website takes
over 1 minute to load and a live audio stream continually "buffers."

I had recently downloaded Bon Echo for Firefox but deleted it b/c I was
not a fan of it. I have noticed this lagging problem since I deleted
it. I am not very computer savvy and need help trying to figure out
what the problem is. Unfortunately, I do not have specifics on the type
of router nor do I have access to it. The administrator is out of town
for several weeks and I cannot get to it.

Please help!!

Thanks