I enjoyed the first couple of runs I did after returning to the game, I'd completely forgotten why I dropped it first time around. By my fourth run I remembered, the lack of a speed up option.

The game really really suffers from no speed up option. Especially when you've got 1 or 2 enemies you will definitely beat taking 20 seconds to get to your kill box. There's waaaay too much down time to keep playing imo.

At the very least there needs to be a "90% wave complete speed up" option or something, the fun of tower defence are not watching every single wave.

There is a speed up mod, see the Guides section. The download is off Steam so you'll need to weigh your tolerance for risk. There are YouTubers, for example Verowak and AlmostCertainly who have Rogue Tower videos with mods if you want verification.