The same thing happens to me too.
With the previous version of PFSENSE it did not happen, and now with version 2.7.2 when I click on client export it takes a long time to load. It must be some error on the part of the package or the 2.7.2 update.
Yes, it is true that I have many certificates created, but before it did not happen and now it does.
Can Netgate fix this?