Is it related to 

#46279 ?

https://bugs.documentfoundation.org/show_bug.cgi?id=46279

no, #46279 deals with restart after installing an extension

LibO crashes for me after I hover for a while in the start center.

Arch Linux 64-bit, KDE Plasma 5
Version: 5.4.0.0.alpha1+
Build ID: 6e4cba99bb35e6697b94309eedd1a08ebea2dc68
CPU threads: 8; OS: Linux 4.10; UI render: default; VCL: kde4; 
Locale: fi-FI (fi_FI.UTF-8); Calc: group
Built on May 5th 2016

..and the UI is crazy and flickering. Not sure what is the point of this extension.

the extension contains 3 configuration files (calc.xcu,writer.xcu,general.xcu),
changing some settings in Tools/Options... to demonstrate, that 
finalized values are not always disabled in UI.

you can find the files in:
.\user\uno_packages\cache\uno_packages\[...].tmp_\finalize_demo.oxt\registry\

a demo setting "VCL/ForceOpenGL" in general.xcu forces OpenGL to be enabled.
this can be the root cause for flickering/crashing.
setting the value to "false" should fix the problem.

Ok, confirmed with Writer options Print - Text placeholder and Print automatically inserted blank pages.

Arch Linux 64-bit, KDE Plasma 5
Version: 5.4.0.0.alpha1+
Build ID: 8891472e1f9c5e452a4e8d55241eeba118274092
CPU threads: 8; OS: Linux 4.10; UI render: default; VCL: kde4; 
Locale: fi-FI (fi_FI.UTF-8); Calc: group
Built on May 12th 2016

This is a somewhat complex report, so let's see what's in the package and what does still apply in a current LO master: 

general.xcu:

	<node oor:name="Misc">
		<!-- Tools/Options.../LibreOffice/General -->
		<prop oor:name="UseSystemFileDialog" oor:type="xs:boolean" oor:op="replace" oor:finalized="true">
- Removed from UI, no longer an issue: https://cgit.freedesktop.org/libreoffice/core/commit/?id=65ee299a0c0e9044d809e58c3c5e75d05ad76f0e

		<prop oor:name="CollectUsageInformation" oor:type="xs:boolean" oor:op="replace" oor:finalized="true">
- Fixed in commit https://cgit.freedesktop.org/libreoffice/core/commit/?id=f4fcec5f0802620192c31aad24db436ead1b2036

		<!-- Tools/Options.../LibreOffice/Advanced -->
		<prop oor:name="ExperimentalMode" oor:type="xs:boolean" oor:op="replace" oor:finalized="true">
- Fixed in https://cgit.freedesktop.org/libreoffice/core/commit/?id=f747390b4f79d88dcccec8aa5e25d3444aac9a23

		<!-- Tools/Options.../LibreOffice/OpenCL -->
		<prop oor:name="UseOpenCL" oor:type="xs:boolean" oor:op="replace" oor:finalized="true">
		<prop oor:name="UseSwInterpreter" oor:type="xs:boolean" oor:op="replace" oor:finalized="true">
- Fixed in https://cgit.freedesktop.org/libreoffice/core/commit/?id=6ebca1d1094d8fd85e485e504e810a1954befcc3

 	<!-- Tools/Options.../LibreOffice/View -->
	<node oor:name="VCL">
		<prop oor:name="ForceOpenGL" oor:type="xs:boolean" oor:op="replace" oor:finalized="true">
		<prop oor:name="UseOpenGL" oor:type="xs:boolean" oor:op="replace" oor:finalized="true">
- Fixed in https://cgit.freedesktop.org/libreoffice/core/commit/?id=81a49f68d61f984503b89e0766bea81ee4733d9c

	<!-- Tools/Options.../LibreOffice/Security -->
	<node oor:name="Security">
		<node oor:name="Scripting">
			<prop oor:name="DisableMacrosExecution" oor:type="xs:boolean" oor:op="replace" oor:finalized="true">
-I can't find this on the UI (anymore?). I know if this is set to true (as a setting, not the finalized attribute) it will disable the Macro Security button on the Security page.
How is this setting being finalized causing a problem?

			<prop oor:name="MacroSecurityLevel" oor:type="xs:int" oor:op="replace" oor:finalized="true">
- Seems to have worked ever since 2004: https://cgit.freedesktop.org/libreoffice/core/commit/?id=58e7ab181880ad71fe2858957f3781c1891ac8f9 

	<!-- Tools/Options.../Load/Save/General -->
	<node oor:name="Save">
		<node oor:name="Document">
			<prop oor:name="LoadPrinter" oor:type="xs:boolean" oor:op="replace" oor:finalized="true">
		<node oor:name="URL">
			<prop oor:name="FileSystem" oor:type="xs:boolean" oor:op="replace" oor:finalized="true">
			<prop oor:name="Internet" oor:type="xs:boolean" oor:op="replace" oor:finalized="true">
-Fixed in https://cgit.freedesktop.org/libreoffice/core/commit/?id=14171010959a4ebf0f6373b6e7f20d1f0741d5a4

Writer and Calc seem to be a bit worse, but the general part is now quite foolproof.

Dear Gabor Kelemen,
This bug has been in ASSIGNED status for more than 3 months without any
activity. Resetting it to NEW.
Please assigned it back to yourself if you're still working on this.

The Writer and Calc settings involved by this example have been fixed by the overall effort to support the finalizing of settings of the Options dialog in meta bug 157698.