Whilst you may see some benefits of enabling host cache, I don't believe this will increase the performace of disk access. I think you are better off drawing out your storage architecture to understand the components involved and their limitations.
What speed HBAs, and FC ports have you got, how many spindles are backing the array, do you have the correct path selection policy set for your LUNs, etc. Look at the performance charts, device queues and latency to see if there are obvious (or any) performance issues and also run some IOmeter benchmarking to see if you are getting the expected IOps and throughput for your storage.
At this stage you should understand the end to end storage stack and be able to answer the question "Are there any issues, and where is the bottleneck?"
Cheers,
Jon
vExpert 2014 - 2022 | VCP6-DCV | http://www.jonmunday.net | @JonMunday77