efficiency of shared hash table

[smsinger3]

Hello. I have a hash table that I share among all sessions of my website. What is the performance if I have many users trying to add and read information at the same time?
Will asp.net make all the other users wait or lock up in some way? I even added a class module that I use as an entry in this hash table. (I'm trying to pass things between modules and not use session variable or the database). Here's what my hash table looks like:

Type Info
department as long
division as long
userclass as clsUser 'Another class module I wrote
End type
Public Shared hshTable as New HashTable()

I then add the Info to the hshTable and use it in many modules.

Is this even a good idea?

Thanks for your help,

SteveS
sms@hmbnet.com