When you downloaded java 64 bit, this does not necessarily mean, than Minecraft is using the latest version you downloaded. Especially, when you use the "New Launcher", it uses its own version of Java. When editing your profile, you can choose, which Java you want to use by specifying the path to the Java executable.
From my experience, Windows 10 PC lag more often than Windows 7 and I believe, this is due to some background cleanup tasks together with some antivirus tools slowing down Disk IO ang enerating a lot of wait fpr your CPUs. Most likely, your Minecraft logs will show some warning about ticks missing and "Can't keep up" etc.
Keeping an eye on the task manager and the IO stats might give you a hint, whats going on.