Especially if you use Zotero, you may want to use PDF XChange as your default PDF browser plugin. After installing PDF XChange, you may still need to do the following:
Open PDF XChange.
Go to the “Edit” menu, and click “Preferences.”
Under “Categories,” click “File Associations.”
Check “Display PDF in browser,” click OK, and close PDF XChange.
Also, if you have the Adobe Acrobat plugin installed in Firefox:
Go to the “Tools” menu, and click “Add-ons.”
Go to the “Plugins” tab, click the “Adobe Acrobat” plugin, and click “Disable.”
Close the “Add-ons” window.
Go to the “Tools” menu, and click “Options.”
Go to the “Applications” tab, and find the content type “Adobe Acrobat Document.”
For this content type, select the “Use PDF XChange Viewer (in Firefox)” plugin for the action type.
Close the “Options” window, and restart Firefox.
Thus far, PDF XChange seems to be working quite well. Comments are not yet searchable in the most recent build, but searchable text from the PDF itself remains searchable. So, at least initially, PDF XChange looks like it might help save trees, cut printing costs, and streamline workflow.