You are looking at it the wrong way. Celeron is a brand which has existed for about 25 years until it was discontinued last year. A laptop with the oldest celeron processors will not be able to run eu4 at all, while some of the newer ones will run eu4 fine, but not particularly fast. Likewise other brands like i5, i7, or ryzen 3/5/7 might be slower or faster than a celeron depending on the model.
Instead I would suggest that you compare benchmarks for the processors of the laptops which are in your price range. For eu4 you would want a CPU with the fastest single core speed, because eu4 does not benefit much from many cores(though it should have at least 2 cores and 4 threads).
And the laptop should have windows 10 or 11 or a recent linux or macOS version, because older operating systems are not supported by the launcher anymore. Windows 11 is better than windows 10, because microsoft will stop distributing free security updates for windows 10 in 2025.
eu4 needs at leas 4 GB of RAM, but I would strongly suggest at least 16 GB if you buy a new laptop and at least 8 GB if you buy a used one. And make sure that it has a SSD and not a HDD. because HDDs are very slow.
