instruction timing for Teensy36

[ossi]

#include <arm_math.h>
#include <arm_const_structs.h>

// instruction times for cortex M4
// http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ddi0439b/CHDDIGAC.html
  
#define nn 10000 
float x,y,sum,T ;
int32_t start,stop ;
 
void setup() {
  
  Serial.begin(115200);  
  delay(2000) ;
  Serial.print("Hello World id=1234\n"); 

  sum=0 ; x=0 ; y=0 ;
  start=micros() ;
  for(int k=0 ; k<nn ; k++){ 
    x += 1.2 ;
    y += 1.3 ;
    sum += x * y ;
    }
  stop=micros() ;
  T=(stop-start)*1e-6 ;
  Serial.printf("sum= %10.2f  cycles:%10.5f\n",sum,T/nn*180e6) ;

  sum=0 ; x=0 ; y=0 ;
  start=micros() ;
  for(int k=0 ; k<nn ; k++){ 
    x += 1.2 ;
    y += 1.3 ;
    sum += x * y ;
    }
  stop=micros() ;
  T=(stop-start)*1e-6 ;
  Serial.printf("sum= %10.2f  cycles:%10.5f\n",sum,T/nn*180e6) ;

  }

void loop(){
  }  

//    4b4: ee37 7a25   vadd.f32  s14, s14, s11     // x+=1.2
//    4b8: ee77 7a86   vadd.f32  s15, s15, s12     // y+=1.3
//    4bc: 3b01          subs  r3, #1                    // k count
//    4be: eee7 6a27   vfma.f32  s13, s14, s15    // sum += x*y
//    4c2: d1f7           bne.n 4b4                      // conditional branch

I am trying to understand the instruction times on the Teensy 36. In order to see the instruction timing for a MAC (Multiply Accumulate) I use the program shown above. This program increments x and y and then sums x*y in sum. The corresponding arm assmbly is given under the source code. Now I have som questions. First: The first loop gives a timing of 6 cycles, the second loop gives a timing of 7 cycles. Is this an alignment problem? If so which instructions depend on alignment? If we take the first case with a cycle time of 6 I would say the instructions vadd take 1 cycle each, the subs will also need one cycle, and the cond. branch will need at least 1 cycle (more likely 2). Thus for the vfma insrtraction remain 6-1-1-1-1=2 cycles, while the manual states that a vfma needs 3 cycles. Are floating point instructions done in parallel to other instructions?