Your best option is going to be to write the results to PI Points because then ProcessBook is just retrieving data rather than retrieving data & calculating - the data chains using the AF Formula could be quite nested and it is an overhead to calculate those on the fly for each client. Being limited by the number of tags is so restrictive & can inhibit innovative solutions so as a side I would challenge to have that changedvia your company/client.
You can alter the Data Update rate for ProcessBook but it will affect the data update rate for all displays. So if for example this is only really affecting the one display then you'll have a knock on to other displays you want to view...and you'll have to do this for each client who may want to view the display. Asle Frantzen wrote a nice blog post about changing the update rate of ProcessBook that you should take a look at: https://pisquare.osisoft.com/community/developers-club/blog/2014/08/01/start-processbook-with-different-update-frequenci…
Thank you for your prompt response. I will advise them that we need to create PI Points in this instance. I thought that might be the case but figured there might be another way.