When comparing Pale Moon vs Slimjet, the Slant community recommends Pale Moon for most people. In the question“What are the best desktop web browsers?” Pale Moon is ranked 5th while Slimjet is ranked 60th. The most important reason people chose Pale Moon is:
"Classic" Firefox add-ons can work, but they are not supported and should be updated or forked to become a Pale Moon add-on.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Has its own add-on ecosystem, built on time-tested technologies such as XUL (plus JS and CSS) and XPCOM
"Classic" Firefox add-ons can work, but they are not supported and should be updated or forked to become a Pale Moon add-on.
Pro Designed for usability, not the shiny new things
Pro Light on resources, although it's not its main focus
Pro Independent from Google and Mozilla
Pale Moon is an independent fork of an older version of Firefox. Therefore, it is independent from Mozilla and are not affected by their terrible decisions such as removing XUL, adding telemetry, pocket, etc.
Pro Customizable
Pro Stable
Pro Support for existing web standards
Pro Respects your privacy
Contains much less spyware than Chrome and Firefox and all of it can easily be disabled.
Pro Open source
So we can verify that the browser is not spyware.
Pro Supports complete themes
Pale Moon supports complete themes, something which Firefox used to have before version 57.
Pro Support for GTK themes
Pale Moon supports your GTK theme while Firefox does not.
Pro Uses Goanna layout engine
Unlike most other browsers, Pale Moon uses its custom engine.
Pro Has its own library of legacy extensions
Pro Very Independent
It isn't controlled by Google nor Mozilla, has its own engine.
Pro Good community support
Pro Optimized for modern processors
Pro Legacy Firefox
Pro Fast and stable
Lower memory footprint and CPU usage than Chromium.
Pro Built-in adblock
Supports adding lists in ublock, adblock, adblockplus, and peerblock/peerguardian text formats.
Pro Allows for no tracking
Has advanced settings to reduce web presence footprint.
Pro Built-in download manager
Multi-threaded streaming download manager with resume functionality. Interrupted downloads will resume when the program is launched again; number of threads and download location customizable on a per-download basis. Actually downloads Linux ISO's from most popular distributions faster than deluge, utorrent, transmission, etc.
Pro Still compatible with Google's ChromeSync functionality
Sign in to back up your extensions and settings, just like always.
Pro Notes plugin available
Pro Easily customize to stop spying verified by OpenSnitch
Just have to dig into all the Settings and disable them starting with SlimJet search.
Pro Customizable options to add additional buttons next to the address bar
Optional buttons such as go to home page, reopen closed tab, go to downloads, go to history and many more.
Pro Built-in Youtube/html5/flash downloader
Allows for downloading both video and extracted mp3 audio, a la Youtube2mp3.
Pro Cross-platform, with zipped portable application available for Windows
You can still bring it with you on a flash drive, even when you're not on Linux.
Pro Screen recording tools built in
Pro Separate from Google's servers and tracking
Pro Integrated shopping and share-to-social-media function
Button is linked to cookies, so doesn't work if signed out (for security/privacy), and also doesn't include any additional tracking like a browser extension would (Facebook, Amazon, etc.)
Pro Verbose resource management
Has a setting to unload tabs from RAM and CPU usage after a customizable threshold number of tabs are open built in.
Pro Idle tab unloading and other advanced features not found in Chrome/Chromium
A lot more configuration options for everything from built in "share to facebook" buttons to options meant to enable optimization on low powered/low RAM systems.
Cons
Con Unsecure
Pale Moon lacks the sandboxing and other privacy protecting features included in latest Firefox releases.
Con Still contains some spyware
Default homepage is spyware and search suggestions and automatic updates are enabled by default.
Con Outdated rendering engine
It is an really old fork of Gecko that misses many of the newer web features.
Con Pale Moon is based on very outdated Firefox code
Con Uses Goanna
It an old Gecko-fork that is developed mainly by one man.
Con Lacks popular extensions and adblockers
It doesn't have ublock origin and umatrix.
Con Does not contain multi-process sandboxing
Con Android version has odd behavior
Clicking does not work.
Con Pale Moon's website is cloudflared
Con WebAssembly enabled by default
Con Lead developer loves Cloudflare and hates Tor
Website is cloudflared and he thinks most sites should be hostile towards tor.
Con Incompetent developers
Con Still based upon Chromium/Chrome
Can yield to bloat if clogged with too many plugins and apps from the webstore.
Con Has some CSS issues on some websites
Has problems loading Sourceforge.com