Can I speed up iCloud photo sync between iPhone and Macbook?
When you take a photo from your iPhone, switch to the Photos app. At the very bottom of the Photos tab, you should immediately see the indicator Uploading…

If your MacBook is plugged in to a power source and/or has the Photos app open, it will download photos as soon as they are in iCloud.

Both your devices need to be connected to Wi-Fi for the aforementioned to occur.

The key is for you to open the Photos app on your iPhone. It used to upload as soon as you connected to Wi-Fi (possibly only if you had sufficient battery), but as of iOS 9 that no longer appears to be the case. I’m guessing this was done to keep from eating up your bandwidth while you may be doing something else.

If you don’t open the Photos app, your iPhone will upload new photos if it is connected to a power source and locked, and it has sufficient battery.

Update: Starting with iOS 10, I am once again seeing immediate uploads of photos from my iPhone when connected to Wi-Fi, whether I’m using the phone or not, and whether connected to a power source or not (might still need to be above 50% battery). Low power mode should be turned off too.