Slic3r not honouring speed

I have been about a month into printing and it seems to be going smooth for the most part.

One thing I am stuck with is Slic3r not honouring the speed I set in its configuration. To speed things up, which I believe the printer can handle, I have set all the speeds in a test slicing config to 160mm/s.

What happens is the first layer is printed real fast, its a 0.3mm layer, then rest of the layers are slooow again, which are set to 0.25mm

I am using Slic3r 0.9.9 and Repitier Host with Sprinter firmware. Printer itself is G1 Mix.

Does anyone know whats going on?

Ok, figured this out. Under cooling, it was enabled. Cooling slows down the print speed based on some formula, disabled that and its printing at configured speeds.

The idea behind the slowdown is a cooling strategy. Its usually done on small layers. You specify the minimum layer time, and if the print time for the layer is less than that, it slows things down enough that the threshold isn't crossed.

This has pros and cons. It is done, theoretically, so that the small layer has time to harden before the hot head come nearby again. The main con is that if the layer is too small, the hot head never leaves.

I have it enabled in conjunction with running fans. Ive had good results with it.

If you want to see the logic behing cooling, this may be useful: [manual.slic3r.org]