Hi Avinash,
This is an hot topic in content switching If using IP src sticky, as it seems you are doing, it wouldn't make much difference tweaking persistent parameter.
However, just for reference, it may occur that CSS may need to switch servers within the same rule due to two particular reasons:
1) sticky cookies/cookieurl/url
2) sorry servers
So, by default the CSS, once matched the content rule, will take only one LB decision per TCP connection, based on the first HTTP request.
With HTTP 1.1 a connection may be used for several requests and responses, and potentially a new LB decision might be needed on each request, if this is the case the CSS needs to be explicitly configured with:
#no persistent
Now regarding flow-timeout-multiplier and sticky-inact-timeout, the former refers to the connection idle timeout parameter, it regulates the time a flow will remain in the connection table while idle. In other words, it is the time period that must elapse for an idle flow before the CSS cleans up the flow.
Sticky-inact-timeout defines the inactivity timeout period on a sticky connection before the CSS removes the sticky entry from the sticky table.
For more details on these parameters check thEse links:
http://www.cisco.com/en/US/docs/app_ntwk_services/data_center_app_services/css11500series/v8.20/command/reference/CmdGrpC.html#wp1139589
http://www.cisco.com/en/US/docs/app_ntwk_services/data_center_app_services/css11500series/v8.20/command/reference/CmdOwCnt.html#wp1141110
