When we were on 12.1, it was all fast. Now we moved to 12.6 and started to get same problems. We ended up embedding the paragraphs in paragraph lists.
I believe the difference started when the selection dialog began to show you the preview of the paragraph as the user selected it. So when you click on an entry, it is going back to the server to get the paragraph for display. You did not say what version you were using. I recall there was a hot-fix created for 12.6.0 where the initial request for the paragraph list would also send down the related paragraphs.That helps tremendously for most cases, unless you have a setup where you have hundreds of paragraphs to select from.
Unlike the old days when patches/hot-fixes were automatically applied to previous releases and made available to all, Oracle dev support tends to only do the version a customer requested and that may be the only customer that sees it. So you will need to contact Support and provide the relevant version information to see if the hot-fix can be applied and given to you.
Mr Peabody-Oracle thanks for the info! I'll get with Oracle support on it. In our production environment we're on 12.0, but we're working on upgrading to 12.6.2. So I can roll the hotfix in with that upgrade hopefully.