IT HAS BECOME our custom to reserve a little space after the local voting for an intemperate word or two excoriating the incompetence of the D.C. election board. So what we are at a loss for, in the light of Tuesday night's flawless performance, is not space - but words. Perhaps it would be churlish to say that we were stunned. Let's leave it that we were tremendously impressed by the efficent work of all the city officials and workers involved - specifically including Shari Kharash, the departing head of the elections board.

Moving next door to Virginia, however, the words that we had become accustomed to using in the District seem remarkably appropriate. Though things appear to be clearing up a little, Virginia seems to have had all kinds of trouble counting, including computer foulups and possible "human errors." The last tallies showed Republican John Warner defeating Democrat Andrew P. Miller for U.S. senator - but, as you surely known, there's been a wee problem about the numbers. Says John S. Mahan, secretary of the Virginia Board of Elections: "I'm really not sure what the outcome is. There is always the possibility of a Miller victory."

At this point we hasten to note that the Virginia board disclaims responsibility for the confusion. The big problem appears to have been a computer in New York operated by the New Election Service, a consortium of news organizations. In processing Virginia returns, the machine failed midway through the count, forcing wire-service officials to rely on a backup system in Richmond. Throughout the night and into the next day, NES officials were reporting results with varying numbers of precincts. That puzzled state officials, who do know for sure that Virginia has 1,857 precincts. Official reports of the counting are still to come.

There were other vote-count foulups around the nation Tuesday night, most noticebale when the races were close. These things happen. The difference is that when they happen in the District of Columbia, any delay is noticed nationally and becomes ammunition for those who argue that the District "is not ready to handle" self-government.That's nonsense, of course, just as it would be nonsense to argue that a smooth vote count would somehow enhance the District's right to self-determination. The point about vote-counting is that, when things go well, people feel a lot more comfortable about the results, the more so when there is a record of things having gone wrong persistently in the past. That's why we are particularly grateful for the good job done in the District Tuesday night.