Conversion of float[] to byte[] is too slow, how to optimize this?

I am making a voxel game, and to save the voxel data, that is a float[,,] variable, I divide then in nine float[] variables( to avoid out of memory issue ), and call the function to convert this float[] to byte[]

here is these function:

 static function float1dprabyte (floataux : float[],zeros : int) {
 var tempo : int =System.Environment.TickCount;
 var intuando : int[]=new int[floataux.Length];
 var byteArray : byte[] = new byte[floataux.Length*4];
 for(var j=0;j<intuando.Length;j++)
 {
 intuando[j]= Mathf.FloorToInt(floataux[j]*(Mathf.Pow(10,zeros)));
 var bytinho : byte[] = new byte[4];
 bytinho =System.BitConverter.GetBytes(intuando[j]);
 byteArray[(j*4)] = bytinho[0];
 byteArray[(j*4)+1] = bytinho[1];
 byteArray[(j*4)+2] = bytinho[2];
 byteArray[(j*4)+3] = bytinho[3];
 }
 tempo -= System.Environment.TickCount;
 Debug.Log("float1dprabyte : "+tempo);
 return(byteArray);
 }
 
 

and to load then i use a reverse function:

 static function byteprafloat (meuint32: byte[],zeros : int) {
 var tempo : int = System.Environment.TickCount;
 var intuando : int[]=new int[meuint32.Length/4];
 var Mx : int = 300;
 var My : int = 120;
 var Mz : int = 300;
 var floataux : float[] = new float[Mx*My*Mz];
 for(var j=0;j<meuint32.Length-4;j+=4)
 {
 intuando[j/4] =System.BitConverter.ToInt32(meuint32,j);
 floataux[j/4] = (1.0*intuando[j/4])/(Mathf.Pow(10,zeros));    
 }
 tempo -= System.Environment.TickCount;
 Debug.Log(" byteprafloat : "+tempo);
 return(floataux);
 }

and this is too slow, 1000 milisseconds for convert a float[300*120*300] into a byte[300*120*300*4] and 3000 miliseconds to convert a byte[300*120*300*4] into a float[300*120*300], with 9 slices of these, to make the complete float[900,120,900] voxel data, the save/load is to much slow...

how I can optimize this?