When comparing st vs Alacritty, the Slant community recommends Alacritty for most people. In the question“What are the best terminal emulators for UNIX-like systems?” Alacritty is ranked 7th while st is ranked 8th. The most important reason people chose Alacritty is:
Written in Rust with a philosophy focusing on speed and simplicity, Alacritty is one of the fastest terminal emulators out there.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Low memory usage
st is built to serve as a lightweight terminal emulator. It's very light and doesn't require many resources to run, making it able to run well on older and low-end machines.
Pro Extremely simple architecture
st consists of a single C file that takes seconds to recompile. This also makes it very easy to understand and customize.
Pro 24-bit "True Color" support
st supports color escape sequences for a full 16 million 24-bit color spectrum, instead of the typical 256 colors.
Pro Support for fontconfig
There is full XFT (X Free Type interface library) and fallback font support through fontconfig in st. If your selected font is missing a certain glyph or symbol, but one of your other installed fonts has it, it will be shown.
Pro Copyfree licensing
Copyfree licensing implies that the user has the freedom to copy, use, modify, and distribute what he/she possesses.
Pro Image previews
Handles image previews (e.g. in ranger) way better than other terminal emulators.
Pro Patches are great
The patches on the site are great. Scroll back, hide the mouse, etc.
Pro Minimalist
Hackable and lightweight.
Pro Blazing fast
it is extremely responsive and fast, even on older computers.
Pro Clean
The terminal doesn't have any bloated features nobody uses. It is very minimal and extendable.
Pro Blazing fast rendering with GPU-accelerated
Written in Rust with a philosophy focusing on speed and simplicity, Alacritty is one of the fastest terminal emulators out there.
Pro Looks good
Alacritty looks very slick on Linux, especially with GNOME or i3.
Pro Simple configuration
The configuration file is very well made and easy to use. You can fine tune your preferences to perfection in a matter of minutes.
Pro Comprehensive font options
Alacritty can be configured to adjust line spacing (height), letter spacing (width), and individual character horizontal/vertical positions.
Pro Has support for image previews in w3m and ranger
Pro Has text ref-low when window is resized
Pro Fast and simple but with true color support
It's simple and fast like xterm or urxvt but with truecolor support which is a big plus if you use a terminal based code editor. Basically Alacritty has all the features you need and nothing you don't (if you're using tmux for multiplexing).
Cons
Con Configuration requires recompiling
Though recompilation takes seconds, knowledge of C header files is required for customization (though it's pretty easy to do for someone who knows how to edit config files).
Con Text is cut off when resizing windows
In the vanilla build, when reducing windows, lines do not wrap, they are cut off. When the window is made large again, some of the text is missing.
Con Crashes when some characters or colored fonts are displayed
Con No scrollback by default
The best way to perform scrollback is to use a multiplexer (such as tmux, screen, or dvtm) if you want scrollback and reverse-search support.
Con New features means installing patches
Just to get copy/paste support and scrolling, you have to install patches. And it's not that intuitive for a beginner.
Con Internal border/margins
Doesn't support internal margins.
Con Source code edits (aka configs) need to be redone after updating
Con Imperfect fontconfig support for CJK characters
It [st] doesn't seem to use CJK fonts provided by fontconfig while other programs use such fonts.
Con Cannot into ligatures
Alacritty does not support ligatures in Fira Code, Iosevka etc.
Con Unreliable Font Rendering
Like a box of chocolate you never know what you're going to get.
Con Sacrifices basic features for raw performance
The Suzuki GSXR of terminals. Or your ditzy, blonde high school cheerleader; fast and pretty but not a lot going on under the hood.
Eschews a negative developmental philosophy towards including said functionality, with the official reason cited in project documentation as "Not within the realm of a terminal emulator" and ostensibly, "best left up to other tools such as terminal multiplexers" [such as screen or tmux]. Which is unfortunate when you factor in speed against terminal with the functionality built in vs their reliance on 3rd party tools:
tmux on alacritty: 'find /usr' time: 3.234s, cpu: 72%
tmux on konsole: find /usr' time: 1.777s, cpu: 96%
See issue here.
