Performance of SYSENTER

I'm testing SYSENTER performance and it turns out that each call takes 54.602287 cycles (1M calls).
0. Is this code correct?
1. Is this treated fast enough?
1.5. I test this due to interest to online judge of special problems with lots of interactives. Usual solutions compile the interactive lib together, making it easily attacked.
2. I run on virtualbox. Does that lead to difference to real computer?
2.5. I was searching for address of HPET but failed and fall back to RDTSC.

Code:

        org $7c00
        cli
        in al,0x92
        or al,0000_0010B
        out 0x92,al
        lgdt [gdt_ptr]
        mov eax, cr0
        inc eax
        mov cr0, eax
        mov ax, 16
        mov ds, ax
        mov ss, ax
        jmp 8:x32
        
        use32
x32:    mov ecx, $174
        xor edx, edx
        mov eax, 8
        wrmsr
        mov eax, 0x7c00
        inc ecx
        wrmsr
        mov eax, intx
        inc ecx
        wrmsr
        
        mov edx, run
        sysexit ; Yes I use SYSEXIT to go to ring3
        
intx:   sysexit

run:    rdtsc
        mov esi, eax
        mov edi, edx
        mov ebx, 1000000
        mov edx, .lp
.lp:    sub ebx, 1
        jz .ok
        sysenter
        
.ok:    rdtsc
        sub eax, esi
        sbb edx, edi
        mov ebx, $b8100
        call print
        mov eax, edx
        call print
        
        jmp $
        
print:  mov cl, al
        and cl, $F
        cmp cl, 10
        jb .ov
        add cl, 7
.ov:    add cl, 48
        mov [ebx], cl
        sub ebx, 2
        shr eax, 4
        jnz print
        sub ebx, 2
        ret
        
        align 8
GDT_BASE:
        dd 0, 0
        dd $FFFF, $00CF9A00
        dd $FFFF, $00CF9200
        dd $FFFF, $00CF9A00 ; No actual protection here
        dd $FFFF, $00CF9200
        GDT_LIMIT = $-GDT_BASE-1
        
        align 8
gdt_ptr:
        dw GDT_LIMIT
        dd GDT_BASE
        
        db $7dfe-$ dup $90
        dw $aa55