The Toronto Rocket subway trains now carrying commuters may be brand new, but they're already suffering from an 'unacceptable' performance.

That's the word in Toronto Transit Commission CEO Andy Byford's latest executive report on the system's overall performance.

While subways are generally running on time, Byford's report notes that trains on the Yonge-University-Spadina line are dragging.

"This line continues to be affected by issues relating to Toronto Rocket (TR) integration," Byford writes. "A high level CEO-to-CEO meeting is being arranged to allow the TTC to impress upon Bombardier the need for substantial improvement in the performance of the TR units as current performance is unacceptable."

The problem stems from the new trains' doors, some of which are malfunctioning and causing delays.

In an email to CTV Toronto, TTC Corporate Communications Executive Director Brad Ross confirmed the meeting scheduled for Friday, noting that the issue with the Bombardier trains is just one of the matters up for discussion.

So far, the TTC has taken delivery of less than half of the 70 Rocket trains due to be put into service by 2014.

When they were first unveiled in 2011, the trains' new design was touted as being roomier and safer as well as more accessible and reliable.

Three levels of government pitched in to underwrite the more than $700-million purchase from Montreal-based Bombardier Inc.

Bombardier is also making the 204 new streetcars, also due to be carrying TTC surface commuters by 2014.