I see. Thanks for the reply!

As my factory has grown larger, I've begun to run into performance issues and when trying to profile the entity times, I noticed that there is a (sometimes large) discrepancy between the entity times of show-time-usage and what show-entity-time-usage shows.
For example, in the screenshot, show-time ...

When placing rails, hovering over the undo button directly after placing a piece of rail resets the planner's start to the start of the previous segment that was just placed.
I would expect that hovering over the undo button does not change from where I am currently placing rails.
This happens every ...

Placing a biolab or inserting an item into it causes the lab to produce a very small but non-zero amount of pollution.
I would expect it to only produce pollution if it is active, i.e. currently researching, however, it does this even in an entirely new save with no research going on. On further ...