Sprite Packer sooooo slow for Android ETC1 sprites (30 mins+)

Hi all, I'm packing 95 sprites into 5 Atlases.

I'm using a computer with a 3.5Ghz i7 and when creating a PC build, the packing takes 10 seconds.

When i create an Android build, it's literally half an hour!!!

I do 'Override for Android' on all my sprites, and have Compression Quality set to Best and 'Compress using ETC1 (split alpha channel)' checked.

But should it really take so much longer? It seems to stay stuck on only a hand full of the 95 sprites, as if it finds a few of the images in particular especially hard to fit to the sheet.

Thanks

p.s. I'm using 5.3.5 but have also found older builds take just as long.

 

Ditto, it takes like an hour on 3.5i7 for 800 sprites ETC2. Have to disable sprite packer for local builds.
Works fine on ios using PVRTC compression though.

Any better alternatives?