fpc is +/- 50mb and Lazarus is +/- 100mb - perhaps not the most suitable software for RPi Full python is similar in size, Lazarus is a bit big, but for other Languages I use Geany, which is not tiny.
But remember you don't need numpy and other huge libraries and most /all you need for making aps comes with it.
It is also a RAD tool so aps are very fast to develop.
Pi3 are not the fastest development boxes
It helps to use piCore instead of Raspbian to get rid of some (a lot) of bloat.
Just found out about zRam.
http://geektillithertz.com/wordpress/index.php/2017/03/16/raspberry-pi-zram/It may not make any difference for normal FPC compiling unless you compile FPC/Lazurus itself
Just did a very quick test last week using Ultibo to do bitmaps text overlay etc.
Got old box with HDMI Graphics display showing bitmaps and sensor data done years ago using Raspbian, Python/Pygame on old model A.
8GB Sdcard image, using about 4.6GB.
Apart from the bitmap files and the lack of antialiasing diagonal lines Ultibo made a kernel.bin of 2.4MB.
The original version that ran on a PC, took 8 months to develop, porting to Pi took 8 days before the weeks of test cycles.
I am making a guess of 8 hours to re-factor from python to pascal and get it running on Ultibo with much less time wasted testing.
I will admit to getting better at coding, but I am not that good
Free Pascal is that good and Lazarus makes it pleasant to use.
But It will make a big tcz