Performance of Vertica

Hi,
I found slower performance of vertica while data is updating. Even I set purge merge out percent at 10%. How can I get fast performance in vertica counts while data is updating? Is there any pools to create specially for count queries and update queries I am in confusion. Please let me know if there any technique to get the fast performance of counts while data is updating.
My case is I have 20 crores of data with 26 columns in that 22 columns of int type and 3 columns are type varchar with varchar(200), varchar(200), varchar(30) and one column is a float. I have vertica on a single node with 256GB RAM.
And let me know which parameters require more memory to do fast updates(for fast updates I am already followed vertica update-delete optimization URL which described in the documentation) and for fast count queries.
My vertica catalog size memory also increasing how to free this memory without restarting the database. I was already followed this URL: https://my.vertica.com/hpe-vertica-troubleshooting-checklists/catalog-size-debugging/ but it does n't give me accurate results.
Thanks in advance.