The new palette panel is not an improvement. It wastes time.
The palette panel that was added since I last updated (was on Musescore 3.X, now I'm on 3.4.2) is very frustrating. You have to click in the panel to get it to scroll. This is a nuisance because before you could just hover over it with the mouse and the scroll wheel would work. It also is annoying since the panel has a lot of stuff you can click that might accidentally edit the score, which wastes time. In addition, when scrolling the box moves smoothly across the screen and takes a while to settle. This makes you overshoot where you want to scroll to and have to wait for the palettes to stop moving. Again, this wastes time for no reason, when the previous non-interpolating scroll worked amazing.
Also, I've noticed that the scrolling box (which includes all of the content, on- or off-screen) will change in size if you have palettes open and scroll. This causes the entire scroll box to jitter on screen, which is annoying. There's no reason for the size of the scrolling box to change, unless it was an attempt to optimize the program.
All of these things stop you from being able to compose quickly using the program. The palette panel is also one of the most often used panels in the entire application, so it shouldn't be so frustrating and buggy.