A fast, lightweight and minimalistic Wayland terminal emulator
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3.8 KiB

Benchmarks

vtebench

All benchmarks are done using vtebench:

vtebench -h $(tput lines) -w $(tput cols) -b 104857600 alt-screen-random-write > ~/alt-random
vtebench -c -h $(tput lines) -w $(tput cols) -b 104857600 alt-screen-random-write > ~/alt-random-colors
vtebench -h $(tput lines) -w $(tput cols) -b 10485760 scrolling > ~/scrolling
vtebench -h $(tput lines) -w $(tput cols) -b 104857600 scrolling --fill-lines > ~/scrolling-filled-lines
vtebench -h $(tput lines) -w $(tput cols) -b 10485760 unicode-random-write > ~/unicode-random

They were "executed" using benchmark.py, which will load each file into memory, and then print it to the terminal. This is done 20 times for each test. Then it calculates the mean and standard deviation for each test.

2020-07-25

System

CPU: i9-9900

RAM: 64GB

Graphics: Radeon RX 5500XT

Terminal configuration

Geometry: 2040x1884

Font: Fantasque Sans Mono 10.00pt/23px

Scrollback: 10000 lines

Results

Benchmark Foot (GCC+PGO) 1.4.2.r14 Alacritty 0.4.3 URxvt 9.22 XTerm 358
alt-random 0.423s ±0.014 0.904s ±0.006 1.111s ±0.003 12.851s ±0.087
alt-random-colors 0.382s ±0.005 0.935s ±0.005 1.146s ±0.007 11.816s ±0.088
scrolling 1.380s ±0.048 1.011s ±0.012 1.021s ±0.016 38.483s ±0.122
scrolling-filled-lines 0.826s ±0.020 1.307s ±0.008 1.213s ±0.015 6.725s ±0.016
unicode-random 0.243s ±0.006 0.091s ±0.003 1 24.507s ±3.264 26.127s ±3.891

2020-07-25

System

CPU: i5-8250U

RAM: 8GB

Graphics: Intel UHD Graphics 620

Terminal configuration

Geometry: 953x1023

Font: Dina:pixelsize=12

Scrollback=10000 lines

Results

Benchmark Foot (GCC+PGO) 1.4.2.r9 Alacritty 0.4.3 URxvt 9.22 St 0.8.4 XTerm 358
alt-random 0.784s ±0.074 1.568s ±0.094 1.600s ±0.052 1.917s ±0.054 34.487s ±0.118
alt-random-colors 0.823s ±0.067 1.627s ±0.107 1.932s ±0.073 2.111s ±0.163 30.676s ±0.127
scrolling 1.612s ±0.092 1.492s ±0.051 1.504s ±0.033 3.767s ±0.140 125.202s ±0.383
scrolling-filled-lines 1.874s ±0.039 2.423s ±0.083 1.994s ±0.037 2.751s ±0.076 19.608s ±0.056
unicode-random 0.458s ±0.026 0.159s ±0.007 1 12.416s ±0.223 crashed 16.336s ±0.410

Alacritty and "unicode-random"

Alacritty is actually really slow at rendering this (whether it is fallback fonts in general, emojis, or something else, I don't know).

I believe the reason it finishes the benchmark so quickly is because it reads from the PTY in a separate thread, into a larger receive buffer which is then consumed by the main thread. This allows the client program to write its output much faster since it is no longer stalling on a blocked PTY.

This means Alacritty only needs to render a couple of frames since it can reach the final VT state almost immediately.

On the other hand, cat:ing the unicode-random test file in an endless loop, or just manually scrolling up after the benchmark is done is slow, which besides being felt (input lag), can be seen by setting debug.render_timer = true in alacritty.yml.