Try wrapping data values in Arc for faster container writes

[GregoryConrad]

Would need to benchmark to confirm speed improvements.

[GregoryConrad]

If we attempt this, which would likely increase write speeds of the container, we could also subsequently consider:

• Remove the Clone requirement (unfortunately, get() would then have to return a ref and users would need to clone everywhere manually)
• Try adding a read_ref for writes and reads to prevent an unnecessary clone when not necessarily needed

[GregoryConrad]

My hypothesis was right, but not to the degree I thought it would be (but still noticeable). For 100,000,000 writes:

Without Arc (seconds)	With Arc (seconds)
84.30227725	78.870126334

Which represents a 6.4% improvement, so I'll keep the change and spin off the possibility of removing the Clone restriction in a new issue.