In Islamic calendar, it’s the month of Ramadhan. This is the month when Muslims around the globe fast from dawn till dusk. It is a special month for Muslims to refrain from temptations, lust etc and do more good to self and others.
Since Malaysia's official religion is Islam, Malaysian generally have a somewhat-altered-daily routine for the month of Ramadhan. For example, for some offices lunch hour might be shortened and office hour ended somewhat earlier. Along with the alter office hour, rush hour somewhat starts earlier. Many restaurants are closed during the day. Nightlife activities (concert etc.) are generally lesser.
These might led foreign tourists to think that visiting Malaysia during Ramadhan would limit their gastronomic experiences since many eateries are close during the day. Actually that is not entirely true. The standard fast food restaurants are open. So are restaurant and eateries operated by non-muslim to cater for non-muslim Malaysians. On top of that, Malaysia have this thing call Pasar Ramadhan.
During the month of Ramadhan, there are lots of Pasar Ramadhan (Ramadhan Market) mushrooming every where in almost every town. This particular market starts everyday around 4pm till around 9pm. These markets specialized in selling food and drinks. It is the best place to sample a wide variety of food. Especially local traditional dish that aren't normally sold during other months. For example, there's this drink called 'Kathira'. It's a concoction of cooling 'herb' and condiments.
Other than Pasar Ramadhan, most hotels have Ramadhan Buffet. Some are a good bargain if you are into sampling food. Be aware that some are total rip-off with overly priced buffet for bad tasting food.
Generally. it is the best time to be in Malaysia to taste local cuisine. Especially when Syawal comes (after Ramadhan ends). Plus, this year, Deepavali (Hindu's celebaration) would be celebrate just a few days before Syawal. But that's a whole different story.