(b) Where functions do make attempts at being correctly rounded
(especially the IBM Accurate Mathematical Library functions), they tend to
be sufficiently slow that the slowness attracts bug reports. Again, this
would likely be addressed by new implementations that use careful error
bounds and information about worst cases to reduce the cost of being
correctly rounding.
I'm not sure that the complaints are about worst cases. More probably
software implementation vs hardware implementation in the average
case. But a new software implementation (better in average) could
help.