With the addition of the sRGB inverse transform, Blender is building upon an entirely unused set of values inherited from the cannibalization of the SPI transform.
Given that Blender will not and can not use values stored to display referred formats that extend into negatives or over values of 1.0 because of the inability to store transforms into EXR files, the vast majority of the gargantuan custom SPI sRGB transform is unused and wasted. Worse, given the numerical quantisation range, the linear to nonlinear transform is inaccurate, representing a mere 1620 values.
That is, of the 65531 values, 1620 are only utilised by Blender, or roughly 2.47% of the entire lookup.
To repair this, replace the sRGB transform with a proper sRGB OETF that defines only the 0.0 to 1.0 range at a high grade 4096 set of intervals, and remove the inverse. The speedup and quality difference achieved should offset the need for an inverse LUT transform.
Example sRGB OETF that would be plug and play https://github.com/sobotka/filmic-blender/blob/master/luts/sRGB_OETF_to_Linear.spi1d.
The following is a Google Spreadsheet visualizing the extent of this transform. The yellow represents values that are impossible to utilize and that represent non-standard SPI specific value ranges. https://docs.google.com/spreadsheets/d/1UMIieLJguMDXsSq6-XbYl1o9CV9xaLnxsUgaht58LeA/edit?usp=sharing