Here are mine on Linux:

Benchmark: timing 50 iterations of berkeley write, file print, file sy
+swrite, file write...
berkeley write: 20 wallclock secs ( 5.60 usr +  3.57 sys =  9.17 CPU) 
+@  5.45/s (n=50)
file print: 24 wallclock secs ( 4.81 usr +  4.31 sys =  9.12 CPU) @  5
+.48/s (n=50)
file syswrite: 24 wallclock secs ( 4.67 usr +  4.21 sys =  8.88 CPU) @
+  5.63/s (n=50)
file write: 26 wallclock secs ( 4.63 usr +  4.15 sys =  8.78 CPU) @  5
+.69/s (n=50)
                 Rate berkeley write     file print file syswrite     
+file write
berkeley write 5.45/s             --            -1%           -3%     
+       -4%
file print     5.48/s             1%             --           -3%     
+       -4%
file syswrite  5.63/s             3%             3%            --     
+       -1%
file write     5.69/s             4%             4%            1%     
+        --
Benchmark: timing 100 iterations of berkeley read, file read, file slu
+rp, file sysread...
berkeley read: 16 wallclock secs ( 3.67 usr +  3.32 sys =  6.99 CPU) @
+ 14.31/s (n=100)
 file read:  9 wallclock secs ( 2.96 usr +  2.25 sys =  5.21 CPU) @ 19
+.19/s (n=100)
file slurp: 12 wallclock secs ( 4.63 usr +  2.26 sys =  6.89 CPU) @ 14
+.51/s (n=100)
file sysread:  8 wallclock secs ( 2.85 usr +  2.05 sys =  4.90 CPU) @ 
+20.41/s (n=100)
                Rate berkeley read    file slurp     file read  file s
+ysread
berkeley read 14.3/s            --           -1%          -25%        
+  -30%
file slurp    14.5/s            1%            --          -24%        
+  -29%
file read     19.2/s           34%           32%            --        
+   -6%
file sysread  20.4/s           43%           41%            6%        
+    --
[download]

Pretty similar, except that syswrite() seems to be a better choice on Linux while read() is a better choice on BSD.