Product Version = NetBeans IDE Dev (Build 201510270002)
Operating System = Windows10 running on amd64
Java; VM; Vendor = 1.7.0_45
Runtime = Java HotSpot(TM) 64-Bit Server VM 24.45-b08

In the native support library for windows there is an unnessesay loop that is actually not needed, original reads;
JNIEXPORT jlong JNICALL Java_org_netbeans_installer_utils_system_WindowsNativeUtils_getFreeSpace0(JNIEnv* jEnv, jobject jObject, jstring jPath) {
    WCHAR*  path = getWideChars(jEnv, jPath);
    jlong  size = 0;
    typedef struct int64s { unsigned long Low, High; } int64t;
    int64t bytes;
    if (GetDiskFreeSpaceExW(path, (PULARGE_INTEGER) &bytes, NULL, NULL)) {
        unsigned long h = bytes.High;
        // workaround of using missing _allmul function
        // replace multiplication by sum
        // (2^32 * high + low) = 2^32 + 2^32 + ... (bytes.High times total) + bytes.Low     
        // can be relatively expensive on big sizes (peta bytes and more)
        while(h > 0) {
            h--;
            size+=4294967296L;
        }
        size+= bytes.Low;
    } else {
        throwException(jEnv, "Native error");
    }
    
    FREE(path);
    
    return size;
}

Could be rewritten as;

JNIEXPORT jlong JNICALL Java_org_netbeans_installer_utils_system_WindowsNativeUtils_getFreeSpace0(JNIEnv* jEnv, jobject jObject, jstring jPath) {
    WCHAR*  path = getWideChars(jEnv, jPath);
    jlong  size = 0;
    typedef struct int64s { unsigned long Low, High; } int64t;
    int64t bytes;
    if (GetDiskFreeSpaceExW(path, (PULARGE_INTEGER) &bytes, NULL, NULL)) {
         size = (bytes.high << 32) + bytes.low;
    } else {
        throwException(jEnv, "Native error");
    }
    
    FREE(path);
    
    return size;
}

or even simpler;

JNIEXPORT jlong JNICALL Java_org_netbeans_installer_utils_system_WindowsNativeUtils_getFreeSpace0(JNIEnv* jEnv, jobject jObject, jstring jPath) {
    WCHAR*  path = getWideChars(jEnv, jPath);
    jlong  size = 0;
    if (GetDiskFreeSpaceExW(path, (PULARGE_INTEGER) &size, NULL, NULL)==0) {
        throwException(jEnv, "Native error");
    }
    
    FREE(path);
    
    return size;
}

This because a jlong is a __int64 as is an ULARGE_INTEGER, the only problem that can occur is that if you have something like a goodzillion petabytes of free diskspace the number returned will be negative as an jlong is signed, but this will be a lot faster.