Laggy backwards-scrolling in multiple applications

[dredmorbius]

I'm noticing that termux is very laggy when scrolling backwards through applications. This occurs both on local and remote (ssh'd oot to other hosts) instances, which makes me suspect the issue is basic terminal functionality.

Example:

• Open Termux
• Open a large manpage using less as the pager. The bash manpage is a good example.
• Skip to the end of the page (G). From here:
• Single-line scrollback is relatively quick: k
• Multi-line scrollback starts lagging: 10k
• A larger scrollback of 100 lines takes ~25 seconds: 100k
• Skipping to the top of the file sees a few seconds of lag, but not as much as the large scrollback: 1G

Vim noticeably doesn't suffer from this (thankfully). Pagers though do.

I'm looking to see if there's a way to access the Termux environment from another terminal to confirm my hunch. The stock Android terminal environment cannot access the Termux files :(

Termux Info

Termux version:
<=0.48
Installed Termux apps:
package:com.termux.api  installer=com.android.vending
package:com.termux  installer=com.android.vending
Updatable packages:
All packages up to date
System information:
Linux localhost 3.10.49-5975984 #1 SMP PREEMPT Thu Oct 8 17:25:20 KST 2015 armv7l Android
Termux-packages arch:
arm
Android version:
5.0.2
Device manufacturer:
samsung
Device model:
SM-T550

stty -g output

4100:5:bf:8a3b:3:1c:7f:15:4:0:1:0:11:13:1a:0:12:f:17:16:0:0:0

Keywords

terminal lag laggy scroll scrollback backscroll

[dredmorbius]

I've confirmed that this behaviour does not exist when accessing termux via busybot's terminal:

• Launch sshd: sshd
• Copy the public key from Connectbot into ~/.ssh/authorized_keys
• Connect from Connectbot to localhost:8022.

Attempt viewing and scrolling forward and backward through the bash manpage as described above.

Result: No lag.

Again, I suspect terminal emulation is the fault.

[ghost]

Should be already fixed (or at least reduce lags) with #628. If not, ask to re-open issue.