Index upgrade problems after cyrus upgrade

[Ramprasad]

I just upgraded cyrus on a busy Imap server from 2.3.x to 2.4.6 , 
problem is with lmtp delivery.

All lmtp deliveries from postfix are hanging forever.
I think this is due to the "Index upgrade" that is going on .. Is there 
a way I can speed up the index upgrade

I have 2000 users and only 200 users index upgrade is complete till now 
in last 4 hours



Thanks
Ram