This was achieved by turning the grid search off in the following system tests:
Relax_disp.test_hansen_cpmg_data_auto_analysis
Relax_disp.test_hansen_cpmg_data_auto_analysis_numeric
Relax_disp.test_hansen_cpmg_data_auto_analysis_r2eff
Relax_disp.test_hansen_cpmg_data_missing_auto_analysis
Relax_disp.test_m61_exp_data_to_m61
Some of the optimisation values are slightly different, or completely different for the one example
of the CR72 model fitted to no exchange, and these have been updated in the tests.