• New strategy for approximate Firth LRT with ultra-rare variants (MAC below 50) by updating log-likelihood only based on variant carriers (can disable using --skip-fast-firth)
• Faster implementation of approximate Firth LRT using customized code for single variant testing as well as better starting values for rare variants (based on Firth without covariates instead of starting at 0)
• Relaxed convergence criterion of Firth LRT from 1E-4 to 2.5E-4