If you primarily want FPS improvements, installing OptiFine on the standard Minecraft launcher gives you significant performance gains without any third-party client.

Yes. Using any unauthorized tool is a violation of Mojang's Terms of Service, which will almost certainly result in a permanent ban for your Minecraft account. Hypixel and other major servers have zero tolerance for this and will permanently ban players caught using cracked clients.

Even on servers that normally whitelist the official Badlion Client, a cracked version may:

The story of the Badlion Client cracked launcher serves as a reminder that, in the world of gaming, innovation and community engagement are crucial, but they must be balanced with sustainable business models and a commitment to protecting creators' rights. The battle may be over, but the war between gamers, developers, and pirates will continue to shape the gaming industry for years to come.

In Minecraft, a standard cracked launcher allows users to play the game offline or on specific "cracked servers" without validating their account through Microsoft's official servers. When applied to Badlion, a "Badlion Client cracked launcher" attempts to spoof the authentication system. This lets offline or non-premium users launch the feature-rich Badlion interface. The Hidden Dangers of Cracked Launchers

Compatibility across numerous popular Minecraft versions, especially 1.8.9, 1.12.2, and the latest versions. Risks and Security Concerns (Crucial)