# Description

For a long time, we have been seeing a slow simulation setup time (i.e.
time spent in `sim.reset` call). It takes around 70-75 seconds to set up
the simulation for ANYmal locomotion task with the new USD asset for it.
This number is only increasing with other more complex robots we have
been trying to import.

The MR dives into the possible causes and gets rid of costly operations.
Many of these are coming from Isaac Sim itself, particularly related to
the initialization of views. Hence, the following breaking changes:

* We no longer depend on Isaac Sim for `RigidPrimView` and
`ArticulationView`. Instead, we directly create underlying PhysX views
for them.
* We add faster reimplementations of functions that are used for regex
matching.

With these changes, the simulation load time is reduced from up to 80
sec to 15 sec. A bulk of the time is still going to setting up the
simulation step for the first time.

## Type of change

- Breaking change (fix or feature that would cause existing
functionality to not work as expected)

## Screenshots

| Before | After |
| ------ | ----- |
|
![orig-fg](https://github.com/isaac-orbit/orbit/assets/12863862/c13f1634-bd2c-4daf-97e0-3b5776b5cd37)
|
![ref-fg](https://github.com/isaac-orbit/orbit/assets/12863862/b509049d-4cbd-45d6-a4f4-6082f4caf7f2)
|

## Checklist

- [x] I have run the [`pre-commit` checks](https://pre-commit.com/) with
`./orbit.sh --format`
- [x] I have made corresponding changes to the documentation
- [ ] My changes generate no new warnings
- [ ] I have added tests that prove my fix is effective or that my
feature works
- [x] I have updated the changelog and the corresponding version in the
extension's `config/extension.toml` file
- [x] I have added my name to the `CONTRIBUTORS.md` or my name already
exists there