Could you let me add additional reproducible step here?
It is reproducible when open Gmail on Chrome.
And I upload videos seeing how slow it is.

1. Go to Settings > Accessibility
2. Enable "Switch Access" service
3. Force stop Chrome
4. Launch Chrome
5. Load gmail.com and log in
6. Open an email 

I attach video.
I want you to share this issue with Google.

Deleted: Accessibility_Switch_Access_On.zip.001 10.0 MB

Accessibility_Switch_Access_On.zip.001 10.0 MB Download

Gentle reminder

Not able to repro with Chrome stable 55.0.2883.87 and Playstore release '55.0.2883.91' based on Comment 1.

Device: Nexus 5X
Android version: 7.1.1

Could you try this on 7.0 N OS device?
And also could you check the reproducible steps in description field?
The key point is that page have many node to render.
So page with many comment like http://pgr21.com/pb/pb.php?id=freedom&no=69979 is a good example here.  

sure. will re-test on OS 7.0 (LG) with the url mentioned.

Device: LG V20
Android version: NRD90M(7.0)

1. Enable Switch access service from Accessibility
2. Force quit the app
3. Visit the "http://pgr21.com/pb/pb.php?id=freedom&no=69979"  link
4. Type text in the upper right edit field.

No issue with keyboard input is being observed.

Please provide what device was specifically used for this test case.
Thanks.

I can see this a clear issue on LG G5/NRD90C, using the link "http://pgr21.com/pb/pb.php?id=freedom&no=69979" 

Will bisect issue.

I doubt this is new.

Enabling any accessibility service slows down Chrome / WebView somewhat.

It appears that this issue is not 100% repro. Please check the video upload.

Device: LGUS992
Android version: 7.0 NRD90C

Thanks.

Please find the video upload at:
http://go/chrome-androidlogs1/6/688278

It is reproducible on all android devices and reproducible on Nexus device, as well.
You can see slow typing and browsing at "google.com" when following steps as below.
1. Go to Settings > Accessibility
2. Enable "Switch Access" service
3. Force stop Chrome
4. Launch Chrome
5. Go to "www.google.com"
6. Search "assistant" and move to "IMAGES" tab to see matched images
7. Type characters for searching (typing is slow) 

Device: Nexus 6/MOB31S
Chrome: 55.0.2883.91

Result: Not able to repro based on comment 19 test steps.
Please check the screen record at: 
http://go/chrome-androidlogs1/6/688278

Using the link "http://pgr21.com/pb/pb.php?id=freedom&no=69979" is the easiest way to reproduce this issue.
Could you check it again with "http://pgr21.com/pb/pb.php?id=freedom&no=69979"?

1. Start Chrome.
2. Enable 'Switch Access' accessibility
3. Visit "http://pgr21.com/pb/pb.php?id=freedom&no=69979"
4. Translate the web page in English.
5. Press in the left most edit field and type text
6. Press in the right most edit field and input text.

Text entry is slow at start and then picks up.
Is this what you see?

Yes, that's what I see.

After enabling "Switch Access" service in Accessibility setting, typing/scrolling get slow.
And after installing an flash alert app and enabling its own service in Accessibility setting, it's reproducible as well.
It is not that frequent to enable "Switch Access" service but it is quite frequent to enable accessibility service of flash alert apps.

For example, here are popular flash alert apps which add their own service to Accessibility for receiving notification.
- Package name : com.fantasticdroid.flashalerts (Flash Alerts on Call / Sms) / Service added to Accessibility: Flash Alerts
- Package name : net.megawave.flashalerts (Falsh Alerts 2) / Service added to Accessibility:Flash Alerts 2
- Package name : com.flexi.flashblinkalert (Flash Alert on Call) / Service added to Accessibility: Flash Alert on Call
App notifications included in"com.fantasticdroid.flashalerts" has users get flash alerts when users receive any Facebook feed if users enable "Flash Alerts 2" service in Accessibility setting.

But the problem is that users can't catch the reason of slow Chrome and don't try to disable services.
So Chrome performance improvement could be the solution for it.

User test reveals that enabling accessibility is the root cause of slow Chrome. 168 issues are reported when conducting usability and 2 issues are relevant to accessibility on. 
 

I've implemented the way displaying warning pop up when enabling accessibility.
Warning pop up says "browser application get slower".
But I'd like Chrome to improve its performance under accessibility and I'll revoke warning pop up once Chrome performance is improved.
So could you take a look at this? 

Gentle reminder

Not able to repro with latest M58 dev release on LG V20
Conditions: Enable 'Switch Access' accessibility
Device: LG V20/NRD90M
Web site tesed on:  "http://pgr21.com/pb/pb.php?id=freedom&no=69979"

Hi Chrome team.

Could you let me upload video and log?
The video and log are about slow browsing symptom on "http://pgr21.com/pb/pb.php?id=freedom&no=69979".

video - ChromeBeta_v58.0.3029.42.zip
log - bugreport_nexus5x.txt

Can you share video with us? Not able to unarchive the zip file on my linux box.

Thanks.

Hi Chrome team, I will upload video to https://drive.google.com.
Could you let me know your account in order to give the account access right?
All I can know here is "ram...@chromium.org" which is abbreviated.

Could not find the reference video in the google drive. can yo attach to this bug report?
Thanks

You could find a video with https://drive.google.com/file/d/0B5mJ6sdg-C-5ZWw2LWNxd2JnTTQ/view?usp=sharing.

Using latest chrome M58, was not able to repro on LG G5/NRD90M.
- Accessibility -> switch access is on
- web site: "http://pgr21.com/pb/pb.php?id=freedom&no=69979"
Was able to enter characters and delete them with reasonable performance in corresponding edit fields.

Dear Chrome engineer,
Thanks for reproducing it but I'm afraid that I don't agree. 
Even though it's a reasonable performance to you, the point is editing and browsing become slow when enabling switch access and it is impacting on user experience badly.

This issue has been Available for over a year. If it's no longer important or seems unlikely to be fixed, please consider closing it out. If it is important, please re-triage the issue.

Sorry for the inconvenience if the bug really should have been left as Available.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

Closing issue.  Please open this bug again if the issue is still occurring.  Thanks!