Opening armory chests in batch takes me 25-30 seconds

So when I open armory chests in batch, it stucks at the last chest and keep me waiting for 20-30 seconds. The amount of batch doesn't matter, it happens whether I am opening 4 at a time or 10.
There is no such thing when I open Resource chests in batch.

I am adding response times to my batch opening requests as well.