OSX Boot drive selection screen is slow, un-responsive and takes forever to load in Macbook Pro (early 2015)
Troubleshooting is often a process of elimination, so it can take time and patience. We'll have to work through these steps one at a time until we can identify the cause and resolve it.

1. Software

As a starting point, I would update macOS Sierra to 10.12.2 (it's been out for about two weeks now).

I'd also ensure you have the latest version of Paragon NTFS for Mac OS X and FUSE for macOS installed.

Once you've ensured you have the latest versions installed, let us know how you go.