Hi, too many sellers, buyers and cash (causes complacency), not enough investment in kit, plus alleged efforts on anti-fraud, very slow indexing, opening new sites when the others could do with upgrading. Will that do for a start, I am sure others can think of more . . .
And umpteeen category expansion changes followed now by reduction in categories to be supeceded by more item specifics that allegedly we want. But just look at eBay boards for the outcries of despairing buyers and sellers. All costs money and diverts their software engineers from making speed improvements.