Spyder 4.0.1 editing *really* laggy

Issue Report Checklist

• Searched the issues page for similar reports
• Read the relevant sections of the Spyder Troubleshooting Guide and followed its advice
• Reproduced the issue after updating with conda update spyder (or pip, if not using Anaconda)
• Could not reproduce inside jupyter qtconsole (if console-related)
• Tried basic troubleshooting (if a bug/error)
  • Restarted Spyder
  • Reset preferences with spyder --reset
  • Reinstalled the latest version of Anaconda
  • Tried the other applicable steps from the Troubleshooting Guide
• Completed the Problem Description, Steps to Reproduce and Version sections below

Problem Description

After updating from the beta4 to 4.0.1 I am experiencing very laggy keyboard responses in the editor. I have turned off Kite and this doesn’t seem to solve the problem, so it appears to be part of the Spyder default (rather than Kite addon) configuration

What steps reproduce the problem?

1. Update spyder to latest 4.0.1
2. Open a new session
3. Start editing a ~1500 line *.py script and watch as key presses are not synced with characters appearing in the editor

What is the expected output? What do you see instead?

Instant keyboard, character appearance

Versions

• Spyder version: 4.0.1
• Python version: 3.7.6
• Qt version: 5.9.7
• PyQt version: 5.9.2
• Operating System name/version: MacOS 10.14.6

Dependencies

applaunchservices >=0.1.7    :  0.2.1 (OK)
atomicwrites >=1.2.0         :  1.3.0 (OK)
chardet >=2.0.0              :  3.0.4 (OK)
cloudpickle >=0.5.0          :  1.2.2 (OK)
diff_match_patch >=20181111  :  20181111 (OK)
intervaltree                 :  None (OK)
IPython >=4.0                :  7.11.1 (OK)
jedi =0.14.1                 :  0.14.1 (OK)
nbconvert >=4.0              :  5.6.1 (OK)
numpydoc >=0.6.0             :  0.9.2 (OK)
pexpect >=4.4.0              :  4.7.0 (OK)
pickleshare >=0.4            :  0.7.5 (OK)
psutil >=0.3                 :  5.6.7 (OK)
pygments >=2.0               :  2.5.2 (OK)
pylint >=0.25                :  2.4.4 (OK)
pyls >=0.31.2;<0.32.0        :  0.31.2 (OK)
zmq >=17                     :  18.1.0 (OK)
qdarkstyle >=2.7             :  2.7 (OK)
qtawesome >=0.5.7            :  0.6.0 (OK)
qtconsole >=4.6.0            :  4.6.0 (OK)
qtpy >=1.5.0                 :  1.9.0 (OK)
rtree >=0.8.3                :  0.8.3 (OK)
sphinx >=0.6.6               :  2.3.1 (OK)
spyder_kernels >=1.8.1;<2.0.0:  1.8.1 (OK)
watchdog                     :  None (OK)
cython >=0.21                :  None (NOK)
matplotlib >=2.0.0           :  None (NOK)
numpy >=1.7                  :  1.17.5 (OK)
pandas >=0.13.1              :  None (NOK)
scipy >=0.17.0               :  None (NOK)
sympy >=0.7.3                :  None (NOK)

[luwil6man]

I have experienced severe lagging since upgrading from Spyder 3 to Spyder 4 on ONLY 1 of 3 computers on which I frequently use Spyder. Hopefully some of the following information based on observation is of some use, let me know if any technical information is desired.

• All 3 computers are PCs and have Spyder 4.0.1 installed, and are used for the same tasks • The highest performing PC is the one with lag. • number of lines in the file, and the number of files open does not effect the severity of lag (this is inconsistent with other comments, although these comments say the lag is “mild”, and I have described it as severe) • lagging gets progressively worse until ~ 1 hour after launching, which is when the degree of lag seems to reach a “steady-state”. • the lag is experienced for all keyboard use in the editor (tabbbing, spacing, backspacing, new lines regular character typing • it is not experienced in the console • disabling all linting and completion in addition to closing panes (with the exception of the editor and console) does not effect the severity

[durack1]

@ccordoba12 @goanpeca thanks for solving this with 4.1.0/4.1.1 folks, I have just noted a bunch of other issues have popped up, but lagginess for me is a thing of the past!