What is the difference in layer time (logarithmic) and layer time (linear) view in the preview?  

RE:

Linear is better if your changes in moves are small, especially if you want to check how specific layers differ but has some limitation in seeing the whole spectrum. For example this is good when comparing for models where print time between layers is similar, such as tubes or truncated pyramids/cones.

Logarithmic helps to quickly spot changes that differ noticeably, this is especially useful when you have very wide range of moves/layers. This is especially useful when comparing printing times where certain layer times are extremely bigger than other, such as spheres and non-truncated pyramids/cones.

Depending on selected mode you can notice differences between layers easier (or not), linear is better to spot differences between adjacent layers if they do not differ much, while logarithmic helps to see better changes between major layer changes (like in your examples between base and the objects placed on the base).

https://en.wikipedia.org/wiki/Logarithmic_scale

RE: What is the difference in layer time (logarithmic) and layer time (linear) view in the preview?

Thank you for the explanation! The actual print showed the same pattern of “roughness” on the walls as the layer time pattern, but I’m struggling to find out why.

I printed a 30x30x150 cuboid for testing, and that one came out nicely, probably because the speed was the same all the way to the top. I suspected the lead screw or belt tensions to be the culprit, but it looks like something else. Any suggestions would be appreciated.