Improve performance by not building schema AST over and over

[mvestergaard]

Each plugin being executed was generating an AST of the schema over and over again, which was especially painful when using near-operations-file.

With this change the AST is built early, and only rebuilt in situations where it isn't passed to the plugin for whatever reason, or a plugin changes the schema.

In my project it decreased execution time from 10s to 4s (250%)

Before

After

There's probably still more that could be done, but this takes care of the worst bits

Addresses the performance issues mentioned on #2069

[mvestergaard]

Another obvious speed improvement, is to make the prettier formatting optional. In the flamegraph above, after these changes, prettier makes up 40-50%

Here's a flamegraph with prettier removed

It brought execution time in my scenario down to 2.5 seconds (another 160%, or 400% total improvement)

[dotansimha]

WOW, that's super interesting. Thank you so much for your efforts!
And you are right, the near-operation-file (and presets in general) is still in experiments. Thank you so much for helping us improving this.