It looks like there are some strange "spike" behavior in the first portion of the DesignBuilder Results Viewer screen shot. This makes me think that the ESO file you've loaded contains data for the summer design day in July as well as the annual simulation. Results Viewer probably isn't separating those periods (design day vs annual) correctly and showing the annual results right after the design day results. I've seen this occur in DView as well when viewing some ESO files.

I think the main reason for this is that in DesignBuilder, you generate IDFs that are either heating design day, cooling design day, or annual (or whatever run period you select). Since this is the approach, DesignBuilder's Results Viewer tool may not have a check for different run periods (i.e., design day vs. annual), and instead be "hard-wired" to show all results from the loaded ESO and lump them into one continuous span of time.

Looking at your comparison to xEsoView, then I would recommend using that tool instead of DesignBuilder's Results Viewer tool (especially if this ESO was generated outside of DesignBuilder for a single simulation that is a combination of design day and annual periods).