Originally Posted by
chx1975
Celeron by itself is not the problem. The names "Celeron" and "Pentium" vaguely mean a slower CPU than i3/i5/i7 but by how much, that's not decided by these names. In short: an U or Y after the model number indicates a usable CPU.
If the CPU has a prefix like D,N,Z,J (not G though!) then it's some sort of Atom. These are - in broad terms - crap, especially in single thread performance. A seven year old desktop CPU wipes the floor with the fastest Atom today (of course, the Atom will have a much lower TDP but that doesn't help in itself it's slowness). Typical names are Atom D525, Pentium N3700, Celeron J1900.
Celeron and Atom are brand names. A Celeron J1900 is not an Atom processor. It's a Celeron processor.
Originally Posted by
chx1975
If the CPU is called Pentium / Celeron some-number and has a postfix like E, U or Y (E is perhaps embedded, U is ultra low I guess, hell knows what Y is but it's even lower TDP than U) then it's a mobile CPU based on the same technology as i3/i5/i7 and has much better single thread performance and not worse overall performance. Typical names: Celeron 847 (I believe this was the last to actually not have an E/U/Y postfix and only three digits so the naming is different), Celeron 1017U, Pentium 3556U. The number of thousands is the generation: the 847 is Sandy Bridge, Celeron 1xxxU is Ivy Bridge, Pentium 2xxxU means Haswell, the 3556U Broadwell, although the Celeron G39* is Skylake. There is some method to this madness just not much. The Y CPUs for Broadwell and Skylake are called "Core M" not Celeron or Pentium.
Categorically, Celeron processors are targeted at budget computers, and performance reflects this. They are much slower compared to Intel's Core processors in the same generation. The Celeron badge is enough reason to look elsewhere.