Editor sluggish on document diagnostics update

Issue Report Checklist

• [x ] Searched the issues page for similar reports
• [ x] Read the relevant sections of the Spyder Troubleshooting Guide and followed its advice
• [ x] Reproduced the issue after updating with conda update spyder (or pip, if not using Anaconda)

Problem Description

On mac (macOS 10.15.5, in this case), the editor in spyder seems to be laggy and slow. Simple tests are fast typing - sometimes it takes seconds to fill all characters. Scrolling is also slow - the editor keeps on rolling for seconds after the wheel on the mouse stops until the “buffer” is worked on… Autocomplete needs up to seconds to react. However, it does not seem to be autocorrect related since disable alls features in this class do not change anything - neither does styles like vertical lines… All tests are on a 4k screen, different scalings tested. The UI seems to be responsive anyway.

What steps reproduce the problem?

1. Start spyder on macOS and start typing in the editor (!not the console - that works fast!)

Paste Traceback/Error Below (if applicable)

PASTE TRACEBACK HERE

Versions

• Spyder version: 4.1.3
• Python version: 3.7.7
• Qt version: 5.12.8
• PyQt version: 5.12.3
• Operating System name/version: macOS10.15.5 (Darwin 19.4.0)

Dependencies

# Mandatory:
applaunchservices >=0.1.7      :  0.2.1 (OK)
atomicwrites >=1.2.0           :  1.4.0 (OK)
chardet >=2.0.0                :  3.0.4 (OK)
cloudpickle >=0.5.0            :  1.4.1 (OK)
diff_match_patch >=20181111    :  20181111 (OK)
intervaltree                   :  None (OK)
IPython >=4.0                  :  7.15.0 (OK)
jedi =0.15.2                   :  0.15.2 (OK)
nbconvert >=4.0                :  5.6.1 (OK)
numpydoc >=0.6.0               :  1.0.0 (OK)
parso =0.5.2                   :  0.5.2 (OK)
pexpect >=4.4.0                :  4.8.0 (OK)
pickleshare >=0.4              :  0.7.5 (OK)
psutil >=5.3                   :  5.7.0 (OK)
pygments >=2.0                 :  2.6.1 (OK)
pylint >=0.25                  :  2.5.3 (OK)
pyls >=0.31.9;<0.32.0          :  0.31.10 (OK)
qdarkstyle >=2.8               :  2.8.1 (OK)
qtawesome >=0.5.7              :  0.7.2 (OK)
qtconsole >=4.6.0              :  4.7.4 (OK)
qtpy >=1.5.0                   :  1.9.0 (OK)
sphinx >=0.6.6                 :  3.1.0 (OK)
spyder_kernels >=1.9.1;<1.10.0 :  1.9.1 (OK)
watchdog                       :  None (OK)
zmq >=17                       :  19.0.1 (OK)

# Optional:
cython >=0.21                  :  None (OK)
matplotlib >=2.0.0             :  3.2.1 (OK)
numpy >=1.7                    :  1.18.5 (OK)
pandas >=0.13.1                :  1.0.4 (OK)
scipy >=0.17.0                 :  1.4.1 (OK)
sympy >=0.7.3                  :  None (OK)

[colinww]

@dalthviz yes I can confirm that disabling just this option (leaving all the other features e.g. code completion, folding, etc) makes a huge improvement in usability.

One thing to note: a big source of slowdown comes with comment blocks """... """ The reason is that I enabled the “automatically insert closing quotes” which is usually quite helpful. But for docstrings, because 3 quotes are needed, there’s always a bit of deleting and re-entering to get the requisite 6 total quotes.

During that time, the editor seems to want to re-lint the whole file, so for example if I have 1k lines of text and I edit a docstring at the top of the file, that moment when I have the un-terminated block comment creates this hiccup where suddenly the whole file is a string, and then it’s not, etc.

Anyway thank you @mrclary and @dalthviz for all the support!

[colinww]

I ran the earlier suggestion of profiling spyder within spyder. The testcase is very simple. I simply browsed the source code of CppHeaderParser : https://pypi.org/project/CppHeaderParser/ The file is lib/python3.7/site-packages/CppHeaderParser/CppHeaderParser.py.

This is a nice long file which essentially kills the spyder editor. I’d estimate seeing the spinning pinwheel 80% of the time while browsing the file, even just scrolling. Pressing “Enter” e.g. a newline, or removing a quotation on a string, etc. All very slow.

spyder_profile_cpp_header_parser.Result.zip