Prerequisites

• Put an X between the brackets on this line if you have done all of the following:
  • Reproduced the problem in Safe Mode: http://flight-manual.atom.io/hacking-atom/sections/debugging/#using-safe-mode
  • Followed all applicable steps in the debugging guide: http://flight-manual.atom.io/hacking-atom/sections/debugging/
  • Checked the FAQs on the message board for common solutions: https://discuss.atom.io/c/faq
  • Checked that your issue isn't already filed: https://github.com/issues?utf8=✓&q=is%3Aissue+user%3Aatom
  • Checked that there is not already an Atom package that provides the described functionality: https://atom.io/packages

Description

When trying to type in front of a bracket and the corresponding closing bracket is located several hundreds of lines later, the editor's frame rate drops significantly and typed characters appear almost half a second later.

Example code:

describe('test', () => {
//      ^ start typing here with cursor in front of the opening (
// ... lots and lots of JS here (1200 SLOC)
})

Steps to Reproduce

1. Open a huge file (tested on JavaScript file with big test suite)
2. Place the cursor in front of the opening bracket while the matching closing bracket is located several hundreds of lines later
3. Attempt to type some characters
4. Observe editor lag

Expected behavior: No editor lag, smooth typing experience, feelings of joy and happiness

Actual behavior: typed characters appear after several hundreds of ms, editor feels unresponsive, feelings of anger and frustration

Reproduces how often: 100% of the time, but only when the matching bracket is very very far away

Versions

Atom    : 1.26.0-beta1
Electron: 1.7.11
Chrome  : 58.0.3029.110
Node    : 7.9.0
OS: MacOS 10.13.4

Additional Information

I am attaching Chrome's performance profile for further inspection. From the stack traces included there I concluded that this is likely a problem with the bracket-matcher package. Disabling the package resolves the issue described here.

I have not looked at the code at all, but it almost seems that bracket-matcher is searching for the matching bracket on each keystroke even though none of the brackets are actually modified, only the content in front of them. 🤔

bracket-matcher.json.zip