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Red Bull team boss Christian Horner says Renault's development rate tests the squad's patience but is wary that significant engine updates will not arrive until the final few races of 2015.
Red Bull has endured a troublesome campaign and the team's relationship with engine supplier Renault has been strained due to the lack of top results.
Horner says that Renault is optimistic over its potential performance gains but accepts that such improvements may not be ready for a couple of months.
"Of course it [waiting] tests our patience," Horner told the Official F1 website.
"Like any competitive team we want performance yesterday, and unfortunately with engines the lead time is a lot longer than with the chassis. Patience is something that we are not really good at. We want to have performance as soon as possible.
"From where the concept is at the moment you are probably looking at least at a couple of months. Two to three months. It needs to happen this year - but also what you learn this year will help you next season."
"As far as I am aware I think that they [Renault] are making good progress on their dyno. They now have some strategic decisions about implementation, and the direction they want to take their development for the rest of this season - and that has an enormous impact on next year."
