An extra count centre is to be introduced in Northern Ireland to avoid a repeat of the chaos which followed a marathon wait for results in 2011.
Only two constituency counts would be held at one location, with all four Belfast constituencies tallied in the city by 2015, chief electoral officer Graham Shields said. Westminster and Northern Ireland Assembly elections are planned for 2015.
Politicians were critical of counting times in the Assembly and local government elections two years ago after a referendum on the voting system at Westminster was held on the same day.
Mr Shields said: "I am now satisfied that the issues that arose during the 2011 polls have been, or will be, satisfactorily addressed before the next major election. However, I do not think it would be prudent to ever again hold three or more polls simultaneously."
Nine count centres would be used instead of eight and all Belfast constituencies would be calculated in the same place. Previously, East Belfast Westminster ballots were tallied in a Newtownards count centre while some other city constituencies were counted at the King's Hall.
Mr Shields's principal concern surrounding the holding of multiple polls at once related to the impact on voters and the likelihood of confusion resulting in spoiled ballots, his written evidence to the Northern Ireland Affairs Committee of MPs said.
"I also have concerns about the operational and logistical demands associated with managing and staffing the counts," he said. "The combination of the Westminster and Northern Ireland Assembly elections planned for 2015 will be particularly challenging, and considerable thought and planning will be required in relation to the arrangements for the counts.
"I acknowledge that the possibility of being asked to hold a third election on the same day is small; however it would, in my view, be extremely unwise to even consider doing so."
He said prolonged counts were an unavoidable feature of Single Transferable Vote (STV) elections and it was almost inevitable that in many cases they will require a second day before results can be declared. "E-counting has been demonstrated to work very well in the Scottish local government elections (in which STV is also used) and there is no reason why it should not work equally well in Northern Ireland," he added. "I remain firmly of the view that e-counting should be introduced."
The matter is being considered by Northern Ireland Secretary Theresa Villiers.