Marca has done an article about the comparation between the situation at the tests of how Toro Rosso and Mclaren are performing so far
but before you delete this post I just want to point out what the article points at the end from internal sourcers
that Mclaren is having problems with the packaging of Renault engine and its cooling that's why they are doing short group of laps
but it is early days to be worried.
http://www.marca.com/motor/formula1/201 ... b45a2.html