Issues resuming from hibernation

I've got a debian stretch installation on a MacBookPro 12,1 (Retina, Early 
2015). When I resume the system from hibernation, the Wi-Fi adapter doesn't 
work any longer. I need to reboot the system to have it work again.

Besides, performance in general is pretty bad after resume. The system is not 
responsive--e.g. windows in the desktop environment take tens of seconds to 
open.

I've got a 7.5 GB swap partition (7812496 KiB), and 7.7 GiB of memory (8079104 
KiB)--actually I chose 8 GB for swap during disk partitioning, but I didn't 
get what I wanted, perhaps because of the giga vs. giga-binary thing.

After a first installation attempt, where I had just 3 or something GB of swap, 
resume after hibernation didn't work at all. I got messages like the 
following:

PM: Image loading progress:   0%
PM: Image loading progress:  10%
PM: Image loading progress:  20%
PM: Image loading progress:  30%
PM: Image loading progress:  40%

and then a black screen.

So I repartitioned the disk, increasing the swap partition, and reinstalled. 
Now the system does start from hibernation, but there are the issues I 
mentioned.

I hope it's not related to a swap partition slightly falling short of RAM. 
Reinstallation is not an option now!

Please let me know what information I should provide, so that you can tell me 
what I need to analyze.

Thanks!