It's not optimisation, it's pessimisation
Attempts by T-Mobile to speed up mobile data connections are breaking websites.
MySociety first publicised  the issue last week.
A developer told us the bug struck while his team was giving a demo to a potential investor. The team subsequently spent two days tracking down what had caused the issue.
MySociety's Matthew Somerville blamed clumsy coding:
The apparent indeterministic nature of the bug – which attacks only occasionally – has made it harder to track down. "We are investigating the issue you have raised and are taking it very seriously," T-Mobile told us. ®