The phrase "lumpy custard" means that the custard, which is a creamy dessert, has small solid chunks in it instead of being smooth and even. Full definition
Any chronic lag was really the fault of whatever software customisation the manufacturer had glooped on top, like a layer of lumpy custard over the system's cogs. (techradar.com)
British climate science denier James Delingpole also delivered a pudding of chilled vexatious abuse with lumpy custard (Delingpole attacked «pause deniers» on the back of a paper that expressly says «we do not believe that warming has ceased»). (theguardian.com)
Any chronic lag was really the fault of whatever software customisation the manufacturer had glooped on top, like a layer of lumpy custard over the system's cogs. (techradar.com)