Work out tlb miss cost instantly with clear inputs, formula shown and shareable results.
A TLB miss triggers a page walk of typically 3-5 dependent memory accesses, costing 50-150 cycles. Large pages attack the miss rate directly: a 2 MB page covers 512 times the memory of a 4 kB page, so the same TLB reaches a vastly larger working set.
TLB cost
cycles per 1000 instructions = accesses x miss rate x page walk cost
TLB reach is entries times page size. Going from 4 kB to 2 MB pages multiplies reach by 512, typically eliminating TLB misses for large working sets.
Internal fragmentation and slower allocation, plus difficulty finding contiguous physical memory once the system has been up a while.