Under the network tab in chrome, I can check the time taken to load a particular file. How can I increase the performance of files such as Workflow.svc, IsEnabled.svc etc, which are taking more time to load now?
Which version are you running?
There's no magic
performance=high setting for any of these services, you need to improve the process as a whole.
For instance, they may be taking too long to read data from the DB, in which case you should make sure DB maintenance is happening regularly, etc. In Web 8+ you can use The Content Manager Tracing Tool to show the actions happening in the system and time take for each, and then use this info to optimize the subsystems where it's taking too long.