Sybase / SQLServer
Microsoft bought Sybase, slapped the SQLServer badge on it, then the coders hit the horror of the code. And proceeded to rewrite the living shit out of it.
I hammered SQLServer ~3yrs ago and was quite happy with it. Found no bugs, predictable behaviour, effortlessly tunable optimisation in the very rare cases you needed it (anyone "requiring" Hint syntax does not understand Indexes and from what I've seen tends to need better understanding of their specific Engine than those who do, which rather defeats Hints' notional purpose), and delightfully had finally implemented result-set calculations. So you can now do running subtotals etc. in SQL just like _WE_ used to casually do in our SQL engine late 80s/early 90s (...)(progress!)
Speed-wise, seemed OK. $value portfolio was A$488bn/nearly half trillion, the feeder system (investment management and accounting) had 3GL code to produce a single day's Trial Balance in ~20mins, which annoyed me because only single day, so I wrote a longish query which produced a whole-of-history Trial Balance with running totals each day for each account for each deal/instrument/trade for each currency (first time in years I've deliberately included a Cartesian Product), which ran in 10-15 seconds.