Apple has released macOS High Sierra 10.13.5 which primarily adds Messages in iCloud support, but it also includes some enterprise and security updates. You can download and install it from the Mac App Store now.
Is you Mac running hot, battery draining fast and apps running poorly? There is some new malware affecting macOS which has started to circulate. Affected macOS systems typically have their processor running at full throttle which can prevent other software from performing optimally.