it is this hard :

This is a 4mm wood drillbit, and it got like that when i was drilling the wood...

For sure, it wasn't a high quality drill bit (quite the contrary) and the tip was a bit dull (hence the force i applied). However, it never happened to me prior to this, even with bent drill bits...

On the other end, metal drill bits drill perfectly trough this hardwood, with clean, nice edges.

However, i had no problem drilling with a quality 4mm wood drillbit (quite a long one, because i had long screws), but i had to be more careful (slower, cleaning the bit more often).