Hello Kunal,
Can you share the syntax of the capture? It might take some space on the buffer on the ASA depending on how you configure it besides that I only see one other thing ( only if its configured with a circular-buffer) that it will take a little of processor of the pix, but I do not think it will make a change of the performance of the ASA, not at all.
Regards,
Julio
Julio Carvajal
Senior Network Security and Core Specialist
CCIE #42930, 2xCCNP, JNCIP-SEC