Hi Vikesh,
I have not personally come across any performance issues with SDM specifically related to Knowledge Management Federated Search, however, if this is a concern, you do have an option here. If the goal is to aleviate or mitigate any risk of effect on the users who are using SDM, then what you can do is create a separate secondary or app server (not sure if you are on conventional or advanced availability architecture) and specifically move just the knowledge daemons (including EBR and federated search related processes) to this additional server, thus eliminating the risk to the end users who are using the other servers to access SDM. This is a much better suited option when using Advanced Availability architecture because each server speaks to the database independently, rather than all db transactions going through the Primary Server, which is the case in Conventional architecture, however, it can be done in either architecture and should work in both.
Hope this helps,
Jon I.