No. Starting the Java Virtual Machine takes some time, but when it is running Java can compete with other compiled languages. To compare the floating point performance of machines or compilers i wrote a small benchmark called MonaBench. This program does 4 million double precision floating point operations.Below you see the results of a Pentium 60 MHz PC running Windows 95.
 

Compiler	[sec]	[mflops]	Floating Point Operations Per Second
LabWindows/CVI  4.0.1 debug	26.7	0.15
Java  JDK1.1.5	6.21	0.64
Turbo C 2.0 optimized for speed	2.31	1.73
LabWindows/CVI  4.0.1	1.67	2.40
MS Visual C++ 5.0  Learning Edition	1.59	2.52
Java  JDK1.1.5 with JIT	1.32	3.03
Java  Netscape 4.0.4 (+JDK1.1)	1.15	3.48

 

Test your own platform with the following Java applet.