LUKS Disk Decryption and Performance Help

I'm currently facing a challenging situation with my disk encryption. I've forgotten the passphrase for my LUKS encrypted disk. Additionally, I've been experiencing slow read/write speeds, which I've attempted to troubleshoot, but without success.

Ideal skills and experience for the job:
- Expertise in LUKS disk encryption
- Experience with data recovery
- Knowledge of disk performance troubleshooting
- Familiarity with Linux systems
- Strong problem-solving skills
- Excellent communication skills