It take a hell lot of time load mail contents, but when I click the previous mail in the same thread and then come back to current mail, it displays the mail contains. PLS fix this!!

Assuming you are using IMAP, by default emClient only downloads the message headers at time of synchronization. The message body is actually downloaded when you open the message, which can cause delays. To avoid this, go to menu/tools/accounts, select the appropriate account and click on the imap tab. Check “Download messages for offline use”. Depending on your internet connection, the initial download could take quite a while…

I am using exchange we service for my mail

Not sure if my comment is applicable for Exchange, as I use gmail.  Maybe other Exchange users can weigh in.  From my experience however, emails load very quickly.