Cool.
147 is lot. To be sure that would be slow and annoying. You said you deleted those. I presume you re-saved. If not, I fear you'll have to re-delete. If you did save, does that solve your problem?
Since both Visio versions exhibited the problem, it would seem there's not a unique to one or the other.
Paul has developed an add-on, Super Utilities, which is a collection of "tools" to augment / provide solutions for frequent tasks that Visio either doesn't have, doesn't exist, or otherwise is obtuse. Minimal cost.
The new GUI, beginning with V2010, packs a lot more, semi steadily available commands. Some are not organized/placed as expected from earlier versions / common sense. But, thru repeated use, you learn the idiosyncrasies. I admit, such was the primary reason for my clutching onto V2007. But once my fingers were pried open, and I experienced the expanded capabilities, object model...well, by V2019, Visio had settled down reasonably well. Before I retired, work had V2010. Ugh! Each successive released version had performance improvements/features.
What specific V2007 features are you interested in?