Fetch the personalized subject line for Message Center broad Logs data

Hi,

We need to fetch the personalized subject line for Message Center broad Logs nms:broadLogEventHisto.

Currently its is stored in the field [delivery/mailParamters/subject].

But it is storing as Hi <%=rtEvent.ctx.firstname%>, where as the expected value is "Hi Lakshmi".
Could any one please let me know the better approach to use activities instead of Javascript, since JS is taking so long time when tried.