Reduce `std` library startup parsing overhead

[NotTheDr01ds]

Reduce `std` library startup parsing overhead

[fdncred]

Just to track it further. Here's what I posted in discord.

This is my WSL

> nu -n
> $nu.startup-time
32ms 480µs 673ns
> exit
> nu -n --no-std-lib
> $nu.startup-time
2ms 998µs 419ns
(difference 29ms 482µs 254ns)

This is my Windows 11 23H2 VM

> nu -n
> $nu.startup-time
28ms 795µs 900ns
> exit
> nu -n --no-std-lib
> $nu.startup-time
7ms 82µs 100ns
(difference 21ms 713µs 800ns)

And my Windows 10 22H2 Desktop

> nu -n
> $nu.startup-time
61ms 399µs 900ns
> exit
> nu -n --no-std-lib
> $nu.startup-time
13ms 14µs 100ns
(difference 48ms 385µs 800ns)

And my MBP M1

> nu -n
> $nu.startup-time
17ms 603µs 750ns
> exit
> nu -n --no-std-lib
> $nu.startup-time
3ms 463µs 500ns
(difference 14ms 140µs 250ns)

[NotTheDr01ds]

Thanks - As mentioned in Discord, mine were slightly better/faster, but that's going to be system dependent, and we need to plan for "worse case" anyway.

While I'm personally not too concerned until my startup times get near 100-250ms (I think), it's clear here that std has a pretty significant bump on the load time that ultimately needs to get rectified. This issue/enhancement is just one (as mentioned, admittedly XY) thought.