It is permissible to read the Quran without performing ablution (wudu) on a computer.
The act of reading the Quran electronically is not considered the same as physically touching the Quran. This is because the Quran is not physically present on the computer screen, but rather displayed as a digital text.
However, it is always recommended to perform wudu before engaging with any Islamic text, including reading the Quran on a computer, as it is a sign of respect and reverence for the holy book.
It is important to note that this applies specifically to reading the Quran on a computer. If you are physically handling a copy of the Quran, then performing wudu is mandatory before touching it.