So far, MPs have dealt with 12 LCO requests from the assembly
A review of how new powers are handed to the assembly says the system is working well, but has faced some "unnecessary" delays in Whitehall.
The Welsh Affairs Committee has dealt with 12 legislative competence orders - or LCOs - over the last two years.
It says it has been an effective way of dealing with requests for new decision-making powers from the assembly.
But it says it now wants monthly updates on the progress of other LCOs, in a bid to cut delays in the process.
Citing "an unacceptable lack of transparency within the Whitehall clearance process" for proposed LCOs, the committee said it would consider calling ministers and UK government officials to give an explanation if MPs remained unhappy with progress.
The system of LCOs means that a request for new powers is first made by the assembly, then the finer details and terms are thrashed out by government officials in Wales and Whitehall.
The draft proposal can then be scrutinised and approved by the Welsh Affairs Committee.
But in one case listed in the 55-page report, a bid to introduce measures forcing building developers to fit sprinkler systems languished in the process for 104 weeks - before it was even handed to the Welsh Affairs Committee.
The committee report said such delays were "highly unsatisfactory".
However, the MPs had overall praise for the way new devolved powers are being delivered.
"We are particularly pleased with the way in which we have worked increasingly and more effectively with our assembly colleagues," said the committee chairman, Dr Hywel Francis MP.
"We will continue to build on the progress made during the last two years to ensure openness, transparency and good governance in the legislative process."
Responding to the report, the Welsh Secretary Peter Hain said he welcomed the findings and looked forward to working with the Welsh Affairs Committee to improver the process "even further".
"I have already freely admitted that the system took time to bed-down, but we've learnt lessons, and things are very different now," said Mr Hain.
"In fact, we are making excellent progress as the process grows in strength, effectiveness and transparency.
Mr Hain insisted that lines of communication between Cardiff Bay and Whitehall are "much clearer than before" and that information is better shared between the two governments.
"But we are not resting on our laurels as I know that this process, like any other, can be fine-tuned," he added.
"We have made a number of improvements to strengthen and quicken the way things are done, at Westminster, around Whitehall and in Cardiff Bay. I therefore look forward to working with members of the Welsh Affairs Committee to further improve what is already a very effective process of devolving powers to Wales."