@Naveen Kumar Kakarla (Quadrant Resource) Biggest cost of enabling it, is that it requires a server restart. Each committed transaction requires 10 bytes in the pg_commit_ts SLRU. In extremely busy systems, contention on that SLRU cache could be observed.
A recent commit made by Álvaro Herrera which has been merged in REL_17_BETA1 branch of the OSS project, introduced several improvements that aim to alleviate performance of subsystems that relied on these SLRUs. No matter what theory can explain about potential impact of enabling this, you should definitely run some collected activity from real-life workload with it disabled, and run it again with it enabled to compare both.
I hope this information helps to understand on Performance and cost.
Regards
Geetha