folded code stuck the scroll

### Prerequisites

* [x] Put an X between the brackets on this line if you have done all of the following:
* Reproduced the problem in Safe Mode: https://flight-manual.atom.io/hacking-atom/sections/debugging/#using-safe-mode
* Followed all applicable steps in the debugging guide: https://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

I have an HTML document with many characters. when folding different parts of the document, the document loses its fluidity.

You can see a video that I recorded of the behavior. in a certain part of the video, you can notice the speed of the scroll between the zone with folded code, and the zone without folded code.

### Steps to Reproduce

*Edit step 2 by @rsese to mention specific lines to fold*

1. save this gist: https://gist.github.com/unluisco/cb6d39da5f33117618dd0ab728219dce
2. open it with atom
3. fold the svg code (lines 18, 29, and 31)
4. scroll it

**Expected behavior:** [What you expect to happen]

I think the scrolling should be fluid

**Actual behavior:** [What actually happens]

the scrolling is stuck.

**Reproduces how often:** [What percentage of the time does it reproduce?]

whenever I fold a lot of code

### Versions

You can get this information from copy and pasting the output of `atom --version` and `apm --version` from the command line. Also, please include the OS and what version of the OS you're running.

Atom : 1.31.2
Electron: 2.0.7
Chrome : 61.0.3163.100
Node : 8.9.3

apm 2.1.1
npm 6.2.0
node 8.9.3 x64
atom 1.31.2
python 2.7.10
git 2.19.1

### Additional Information

Any additional information, configuration or data that might be necessary to reproduce the issue.

this is the video: https://www.dropbox.com/s/b23i0cmzf2hdzem/atom.mp4?dl=0