Multi INSERT Command (no replies)

Dear Forum

I have to insert in a table 300 record (3 column /1 record )long approximatly 500bytes in total. Programming in C#.

I need for this around 6 second.After 6 second, the software stop in a breakpoint
insid a if like this:

if (Insert>300) ..breakpoint

I noted, that if i dont use 300 INSERT but 150 ,everyone whit 2 record, total time is less.

So question are:
-Why ?
-Do you have other advice for reduce this time (software advice)
-What performace i must aspect teorycally ( byte/sec ) in o normal home PC
and what can be the next hardware step.

Many many hello for reply

Roberto