I've been a toad user for a long time and have really just dealt with the issue of editing a subquery being so slow. Selecting and deselecting a column for instance can take minutes. Lately I've had to use subqueries more frequently and I'm frustrated enough now to reach out. Please help.
Welcome to the TDP forum, Pat.
Can't mention much relief, given we're not seeing the nature of your query/s or how you're attempting to edit the subqueries within the product, but I have not experienced this issue to date, at least not with the latest 6.x releases. What version of TDP are you on?
That said, I'd reach out to Quest Support so they can document your approach, and subsequent issue. I do see from Quest's Knowledge Base that there were similar issues in older versions of TDP, but looks like these have been resolved in later versions (see here and here, for example.)