What to do with Java BigDecimal performance?
I write currency trading applications for living, so I have to work with monetary values (it's a shame that Java still doesn't have decimal float type and has nothing to support arbitrary-precision monetary calculations). "Use BigDecimal!" — you might say. I do. But now I have some code where performance is an issue, and BigDecimal is more than 1000 times (!) slower than double primitives.
The calculations are very simple: what the system does is calculating a = (1/b) * c many many times (where a, b and c are fixed-point values). The problem, however, lies with this (1/b). I can't use fixed point arithmetic because there is no fixed point. And BigDecimal result = a.multiply(BigDecimal.ONE.divide(b).multiply(c) is not only ugly, but sluggishly slow.
What can I use to replace BigDecimal? I need at least 10x performance increase. I found otherwise excellent JScience library which has arbitrary-precision arithmetics, but it's even slower than BigDecimal.
Any suggestions?
Answer
May be you should start with replacing a = (1/b) * c with a = c/b ? It's not 10x, but still something.
If I were you, I'd create my own class Money, which would keep long dollars and long cents, and do math in it.