slow as hell packaging when `package.individually: true`

[pkit]

Are you certain it's a bug?

• [X] Yes, it looks like a bug

Are you using the latest plugin release?

• [X] Yes, I'm using the latest plugin release

Is there an existing issue for this?

• [X] I have searched existing issues, it hasn't been reported yet

Issue description

Essentially a reopen of #183

Currently it takes over 100 seconds per lambda. I.e. 3 lambdas >300 seconds. The machine is a 24CPU+128GB RAM+2TB 5GB/sec SSD What does it do???

Service configuration (serverless.yml) content

N/A

Command name and used flags

N/A

Command output

N/A

Environment information

Latest for both.