Stack smash on sys context

[bertmelis]

Stack smashing detected.

Exception (5):
epc1=0x401007c6 epc2=0x00000000 epc3=0x00000000 excvaddr=0x00000000 depc=0x00000000

>>>stack>>>

ctx: sys
sp: 3fffff90 end: 3fffffb0 offset: 0000
3fffff90:  3fffdad0 00000000 3fffdab0 401007c6  
3fffffa0:  3fffdad0 00000000 3fffdab0 4021433c
<<<stack<<<

I'm sending apparently a lot of data to WiFiClient, resulting in stack smashing. I actually don't know how to solve this one.
Tips are welcome!

[bertmelis]

I was building in debug mode. Switching to release, also with much less output on Serial, the problem went away.

I'm not convinced of this solution though.