Hi Raj
1. During the time when there are lot of dumps as you mentioned, you can enable the trace by using the transaction code ST12, and then check the over all usage of ABAP & DB,
2. If you know the transaction code which is having performance issue you can check that explicitly from ST12.
3. You can find the transaction or program which is causing the dumps from the dump analysis itself in the option "Users and transactions", and put the trace on that program. Once you get the trace result, analyse it to find which statement appears to be expensive.
4. ST03 or ST03n also will be of great help for the analysis.
BR
SS