i'm not even sure it would be more performant

if (Vector128.IsHardwareAccelerated && typeof(T) == typeof(float))
{
    return Unsafe.BitCast<Vector3<T>, Vector3>(this).AsVector128().Equals(Unsafe.BitCast<Vector3<T>, Vector3>(other).AsVector128());
}

if (Vector128.IsHardwareAccelerated && typeof(T) == typeof(float))
{
    return Unsafe.BitCast<Vector3<T>, Vector3>(this).AsVector128().Equals(Unsafe.BitCast<Vector3<T>, Vector3>(other).AsVector128());
}

; Assembly listing for method NumTests:TestNum(System.Numerics.Vector4,System.Numerics.Vector4):bool (FullOpts)
; Emitting BLENDED_CODE for X64 with AVX - Windows
; FullOpts code
; optimized code
; rsp based frame
; partially interruptible
; No PGO data
; 0 inlinees with PGO data; 1 single block inlinees; 2 inlinees without PGO data

G_M000_IG01:                ;; offset=0x0000
       vzeroupper 
 
G_M000_IG02:                ;; offset=0x0003
       vmovups  xmm0, xmmword ptr [rcx]
       vmovups  xmm1, xmmword ptr [rdx]
       vcmpps   xmm2, xmm0, xmm1, 0
       vcmpps   xmm0, xmm0, xmm0, 0
       vcmpps   xmm1, xmm1, xmm1, 0
       vorps    xmm0, xmm0, xmm1
       vpcmpeqd xmm1, xmm1, xmm1
       vxorps   xmm0, xmm0, xmm1
       vorps    xmm0, xmm2, xmm0
       vpcmpeqd xmm0, xmm0, xmm1
       vpmovmskb eax, xmm0
       cmp      eax, 0xFFFF
       sete     al
       movzx    rax, al
 
G_M000_IG03:                ;; offset=0x003D
       ret      
 
; Total bytes of code 62

; Assembly listing for method NumTests:TestMan(Vector4`1[float],Vector4`1[float]):bool (FullOpts)
; Emitting BLENDED_CODE for X64 with AVX - Windows
; FullOpts code
; optimized code
; rsp based frame
; partially interruptible
; No PGO data
; 0 inlinees with PGO data; 1 single block inlinees; 2 inlinees without PGO data

G_M000_IG01:                ;; offset=0x0000
       vzeroupper 
 
G_M000_IG02:                ;; offset=0x0003
       vmovups  xmm0, xmmword ptr [rdx]
       vmovups  xmm1, xmmword ptr [rcx]
       vcmpps   xmm2, xmm1, xmm1, 0
       vcmpps   xmm3, xmm0, xmm0, 0
       vorps    xmm2, xmm2, xmm3
       vpcmpeqd xmm3, xmm3, xmm3
       vxorps   xmm2, xmm2, xmm3
       vcmpps   xmm0, xmm1, xmm0, 0
       vorps    xmm0, xmm0, xmm2
       vpcmpeqd xmm0, xmm0, xmm3
       vpmovmskb eax, xmm0
       cmp      eax, 0xFFFF
       sete     al
       movzx    rax, al
 
G_M000_IG03:                ;; offset=0x003D
       ret      
 
; Total bytes of code 62

; Assembly listing for method NumTests:TestNum(System.Numerics.Vector4,System.Numerics.Vector4):bool (FullOpts)
; Emitting BLENDED_CODE for X64 with AVX - Windows
; FullOpts code
; optimized code
; rsp based frame
; partially interruptible
; No PGO data
; 0 inlinees with PGO data; 1 single block inlinees; 2 inlinees without PGO data

G_M000_IG01:                ;; offset=0x0000
       vzeroupper 
 
G_M000_IG02:                ;; offset=0x0003
       vmovups  xmm0, xmmword ptr [rcx]
       vmovups  xmm1, xmmword ptr [rdx]
       vcmpps   xmm2, xmm0, xmm1, 0
       vcmpps   xmm0, xmm0, xmm0, 0
       vcmpps   xmm1, xmm1, xmm1, 0
       vorps    xmm0, xmm0, xmm1
       vpcmpeqd xmm1, xmm1, xmm1
       vxorps   xmm0, xmm0, xmm1
       vorps    xmm0, xmm2, xmm0
       vpcmpeqd xmm0, xmm0, xmm1
       vpmovmskb eax, xmm0
       cmp      eax, 0xFFFF
       sete     al
       movzx    rax, al
 
G_M000_IG03:                ;; offset=0x003D
       ret      
 
; Total bytes of code 62

; Assembly listing for method NumTests:TestMan(Vector4`1[float],Vector4`1[float]):bool (FullOpts)
; Emitting BLENDED_CODE for X64 with AVX - Windows
; FullOpts code
; optimized code
; rsp based frame
; partially interruptible
; No PGO data
; 0 inlinees with PGO data; 1 single block inlinees; 2 inlinees without PGO data

G_M000_IG01:                ;; offset=0x0000
       vzeroupper 
 
G_M000_IG02:                ;; offset=0x0003
       vmovups  xmm0, xmmword ptr [rdx]
       vmovups  xmm1, xmmword ptr [rcx]
       vcmpps   xmm2, xmm1, xmm1, 0
       vcmpps   xmm3, xmm0, xmm0, 0
       vorps    xmm2, xmm2, xmm3
       vpcmpeqd xmm3, xmm3, xmm3
       vxorps   xmm2, xmm2, xmm3
       vcmpps   xmm0, xmm1, xmm0, 0
       vorps    xmm0, xmm0, xmm2
       vpcmpeqd xmm0, xmm0, xmm3
       vpmovmskb eax, xmm0
       cmp      eax, 0xFFFF
       sete     al
       movzx    rax, al
 
G_M000_IG03:                ;; offset=0x003D
       ret      
 
; Total bytes of code 62

public struct Vector4<T> where T: IEquatable<T>
{
    T x;
    T y;
    T z;
    T w;
    [MethodImpl(MethodImplOptions.AggressiveInlining | MethodImplOptions.AggressiveOptimization)]
    public bool Equals(Vector4<T> other)
    {
        if (Vector128.IsHardwareAccelerated && typeof(T) == typeof(float))
        {
            return Unsafe.BitCast<Vector4<T>, Vector4>(this).AsVector128().Equals(Unsafe.BitCast<Vector4<T>, Vector4>(other).AsVector128());
        }
        return other.x.Equals(x) && other.y.Equals(y) && other.z.Equals(z) && other.w.Equals(w);
    }
}
public static class NumTests
{
   static bool TestNum(Vector4 l, Vector4 r)
    {
        return l.Equals(r);
    }

    static bool TestMan(Vector4<float> l, Vector4<float> r)
    {
        return l.Equals(r);
    }
}

public struct Vector4<T> where T: IEquatable<T>
{
    T x;
    T y;
    T z;
    T w;
    [MethodImpl(MethodImplOptions.AggressiveInlining | MethodImplOptions.AggressiveOptimization)]
    public bool Equals(Vector4<T> other)
    {
        if (Vector128.IsHardwareAccelerated && typeof(T) == typeof(float))
        {
            return Unsafe.BitCast<Vector4<T>, Vector4>(this).AsVector128().Equals(Unsafe.BitCast<Vector4<T>, Vector4>(other).AsVector128());
        }
        return other.x.Equals(x) && other.y.Equals(y) && other.z.Equals(z) && other.w.Equals(w);
    }
}
public static class NumTests
{
   static bool TestNum(Vector4 l, Vector4 r)
    {
        return l.Equals(r);
    }

    static bool TestMan(Vector4<float> l, Vector4<float> r)
    {
        return l.Equals(r);
    }
}