I bought my MacBookPro not a long while ago, but it had this problem from the beginning. If this matters, I bought it in China. All of the websites I need work fine on my IPhone though.
I did the test as you suggested, here are the results:
System Version: macOS 10.12.5 (16F73)
Kernel Version: Darwin 16.6.0
Boot Mode: Normal
Model: MacBookPro13,1
User diagnostics
2017-06-02 com.apple.WebKit.WebContent crash
2017-06-02 com.apple.WebKit.WebContent crash
2017-06-02 com.apple.WebKit.WebContent crash
2017-06-02 com.apple.WebKit.WebContent crash
2017-06-02 com.apple.WebKit.WebContent crash
2017-06-02 com.apple.WebKit.WebContent crash
2017-06-02 com.apple.WebKit.WebContent crash
2017-06-02 com.apple.WebKit.WebContent crash
2017-06-02 com.apple.WebKit.WebContent crash
2017-06-08 SourceKitService crash
Total CPU usage: user %, system %
CPU usage by process "Terminal" with UID 501: 12.6%
Loaded extrinsic kernel extensions
com.intel.driver.EnergyDriver (2.0) UUID
Extrinsic daemons
com.adobe.fpsaud
org.macosforge.xquartz.privileged_startx
Extrinsic agents
com.skype.skype.shareagent
com.openssh.ssh-agent
com.valvesoftware.steamclean
org.macosforge.xquartz.startx
com.Arturia.ArturiaSoftwareCenterAgent
com.google.keystone.user.agent
launchd items
/Library/LaunchAgents/com.Arturia.ArturiaSoftwareCenterAgent.plist
(com.Arturia.ArturiaSoftwareCenterAgent)
/Library/LaunchAgents/org.macosforge.xquartz.startx.plist
(org.macosforge.xquartz.startx)
/Library/LaunchDaemons/com.adobe.fpsaud.plist
(com.adobe.fpsaud)
/Library/LaunchDaemons/org.macosforge.xquartz.privileged_startx.plist
(org.macosforge.xquartz.privileged_startx)
Library/LaunchAgents/com.google.keystone.agent.plist
(com.google.keystone.user.agent)
Library/LaunchAgents/com.skype.skype.shareagent.plist
(com.skype.skype.shareagent)
Library/LaunchAgents/com.valvesoftware.steamclean.plist
(com.valvesoftware.steamclean)
Extrinsic loadable bundles
/System/Library/Extensions/advKorgUSBMIDIDriver.plugin
(jp.co.korg.advKorgUSBMIDIDriver2)
/System/Library/Extensions/NIUSBAudioDriver.kext
(com.caiaq.driver.NIUSBHardwareDriver)
/System/Library/Extensions/NIUSBGuitarRigMobile.kext
(com.caiaq.driver.NIUSBGuitarRigMobileDriver)
/System/Library/Extensions/RemoteVirtualInterface.kext
(com.apple.nke.rvi)
/Library/Audio/MIDI Drivers/KorgUSBMIDIDriver.plugin
(jp.co.korg.KorgUSBMIDIDriver)
/Library/Audio/MIDI Drivers/NIUSBMIDIDriver.plugin
(No bundle ID)
/Library/Audio/Plug-Ins/Components/Analog Lab.component
(com.Arturia.Labo2.audiounit)
/Library/Audio/Plug-Ins/Components/Guitar Rig 5.component
(Guitar Rig 5.MusicDevice.component)
/Library/Audio/Plug-Ins/Components/Jupiter-8 V2.component
(com.arturia.jupiter8v2.au)
/Library/Audio/Plug-Ins/Components/Oberheim SEM V.component
(com.Arturia.Oberheim-SEM-V.audiounit)
/Library/Audio/Plug-Ins/Components/Spark.component
(com.arturia.Spark)
/Library/Audio/Plug-Ins/VST/Analog Lab.vst
(com.Arturia.AnalogLab.Vst2)
/Library/Audio/Plug-Ins/VST/Guitar Rig 5.vst
(Guitar Rig 5.FX.vst)
/Library/Audio/Plug-Ins/VST/Jupiter-8 V2.vst
(com.arturia.jupiter8v2.vst)
/Library/Audio/Plug-Ins/VST/Oberheim SEM V.vst
(com.Arturia.Oberheim-SEM-V.Vst2)
/Library/Audio/Plug-Ins/VST/Spark.vst
(Spark)
/Library/Audio/Plug-Ins/VST3/Analog Lab.vst3
(com.Arturia.AnalogLab.Vst3)
/Library/Audio/Plug-Ins/VST3/Oberheim SEM V.vst3
(com.Arturia.Oberheim-SEM-V.Vst3)
/Library/Extensions/EnergyDriver.kext
(com.intel.driver.EnergyDriver)
/Library/Internet Plug-Ins/Flash Player.plugin
(com.macromedia.Flash Player.plugin)
/Library/PreferencePanes/Flash Player.prefPane
(com.adobe.flashplayerpreferences)
/Library/PreferencePanes/NIUSBAudio.prefPane
(com.caiaq.NIUSBAudioPreferencePane)
Library/Address Book Plug-Ins/SkypeABCaller.bundle
(com.skype.SkypeABCaller)
Library/Address Book Plug-Ins/SkypeABChatter.bundle
(com.skype.SkypeABChatter)
Library/Address Book Plug-Ins/SkypeABDialer.bundle
(com.skype.SkypeABDialer)
Library/Address Book Plug-Ins/SkypeABSMS.bundle
(com.skype.SkypeABSMS)
Proxies
ProxyAutoConfigEnable : 1
ProxyAutoConfigURLString : http://127.0.0.1:8090/proxy.pac
hosts format: ASCII text
User login items
NIHardwareAgent
Safari extensions
Keeper® Password Manager & Digital Vault
com
Restricted user files: 51
Elapsed time (s): 41