As in if you press left or right does it scroll too fast?
Or when you use the right mouse button to explore the map does it move too fast?

It does move pretty fast on my system, but it's totally manageable.

Its scrolls too fast, is there a way to tone it down or scroll slower?

I don't have the issue, but that's because the scrolling is position relative. Try keeping the cursor closer to where you click. Like scrolling in a document.

It scrolls all the way across the map for me, even if I scroll-move only a few pixels...

Edit: This was at the initial 800x600 resolution. It got much better after I increased it to 1280x800.

3 years later machines are even faster.

I can start have in Windows 10 only with SC3U.exe" -w -r:800x600 on Nvidia, when i try to set other resolution ingame im gettin only small picture.. not full screen with black bars in for 4:3 but original resolution, maybe it can be somehow adjusted by Nvidia panel on per game basic.. I dont want to set it for all game, because for other games its working correctly..

I tried of course SC3U.exe" -w -r:1280x1024.

My screen is 16:10 - 1920:1200

If you want to make sure the game and not the video card/drivers is the problem you need to change the options in the NVidia control panel in 'Display' > 'Adjust desktop size and position' > 'Scaling' tab > select the 'Aspect ratio' radial and activate 'Override the scaling mode set by games and programs' check box.

That last check box especially could be your reason to have other full screen programs run correctly while SC3000 does not.

In case those are already the options selected and the game has the issue you say, then it's a problem between the game, your drivers and the OS. In other words, practically anything.

I'm also having a problem with this.

I'm hoping there will be an open source project that fixes this. I don't regret buying this game but sometimes these games aren't a good experience. Lock's Quest is another one I enjoyed much more on the original platform than the GOG version later on.

Yeah, using the right mouse button or arrow keys makes the camera move WAY too fast for me. I've been asking around, but I haven't found an answer.

Use my guide to get the game running using DxWnd.
DxWnd has a built-in framerate limiter that will mostly fix the main problem. And if you want you can follow the extra steps to make the UI/fonts look bigger on the screen.
(or any other framerate limiter tool like DxTory for that matter... but DxTory isn't able to scale up the window to make the fonts look bigger though)

https://www.gog.com/forum/simcity_series/fixed_these_problems_using_dxwnd_map_scrolling_speed_high_cpu_usage_small_textui/page1