NodeMCU 0.9 vs 1.0 targets w/Arduino - major differences in compiled code?

[mortrek]

I have a fairly simple Arduino IDE project where I accidentally compiled for NodeMCU 0.9 (ESP-12) and it was actually a NodeMCU 1.0 (ESP-12E). The 0.9 version worked, but was occasionally unstable and would throw an exception/lock up a few times a day. Since changing it to NodeMCU 1.0, it has worked flawlessly.

I'm curious as to why? All the info I've found says that the 12 and the 12E are almost identical except for a few extra IOs. Based on my results, there has to be more to it than that, right? Maybe a difference between NodeMCU versions, unrelated to the ESP8266 module itself?

I'm using the ESP8266 Arduino library 2.7.4 with Arduino 1.8.12. I'm not doing anything fancy with it, mainly just connecting to wifi, serving webpages, and controlling some digital output pins.

edit: I cannot seem to find the original ESP-12 datasheet, so I can't even make comparisons between the two that way...

Also boards.txt is almost identical between the two. Running diff shows the only significant difference is that the 0.9 uses qio, 1.0 uses dio for flash mode.

[bizkits]

Could it be in the newer version, they fixed some memory issues or optimized some of the codes?