Please explain the appropriate places where jsps can be used and places where servlets can be used on performance basis

JSP's also become servlets ultimately.But the difference I guess lies in the fact that the machine generated servlet(in the case of JSP) might not be optimised for speed.Manually written servlets may be optimised for performance.

well the usual point to be noted is that jsps are meant to reduce the headache of the programmer from typing in unwieldy code into the servlets. but i am not sure how much of this has been actually achieved, i mean typing in java code into jsps is equally cumbersome.
well, the point is as far as performance is concerned i don't think a significant difference exists between jsps and servlets and i don't think optimization is better done 'coz the container writes OPTIMIZED code.
well i suggest you go about using a combination of jsps and servlets and ofcourse javabeans. push most of the presentation logic into the jsps, business logic into servlets and temporary placeholding logic into the beans. i guess that about answers it.