Via Harry Hutton, there were in the past problems with measuring the speed at which women became sexually aroused.

Earlier attempts to record sexual arousal have involved invasive
probes and electrodes, according to Tuuli Kukkonen, who helped conduct
the study led by Irv Binik at McGill University Health Centre in
Montreal, Canada.

For
women participating in previous studies, this sometimes meant the use
of an uncomfortable probe similar to a tampon, inserted into the vagina.

Such
invasive methods “made studying sexual arousal very difficult” and
comparing sexual response between men and women even more challenging,
says Kukkonen, as the measurement techniques differed between the sexes.

Incredibly surprising that difficulty, don’t you think? Still good news:

Women may have a reputation for demanding lengthy foreplay, but they
become sexually aroused as quickly as men, according to a new study
that used thermal imaging to measure increased blood flow to genital
regions.

While watching pornography, both sexes reach peak arousal within 10 minutes, on average, researchers report.

Still quite a long time there. I think it was Johnny Rotten who described sex as ‘ two minutes of squelching’. A five to one ratio?