Thank you for your comment. Sorry about delayed reply. I've had a quick look at IDF, agree, must try that sometime.

I'm using a NodeMCU 0.9 (ESP-12 Module) and the Arduino IDE. A minimal program with only empty functions setup(){} and loop(){} takes 51 seconds to compile (and load), and it's quite big. IROM : 228400 - code in flash (default or ICACHE_FLASH_ATTR) IRAM : 26352 / 32768 - code in IRAM (ICACHE_RAM_ATT...