Based on the time difference you are seeing, you are likely using Python 2.x. In Python 2.x, the decimal module is written in Python and is rather slow. Beginning with Python 3.2, the decimal module was rewritten in C and is much faster.

Using Python 2.7 on my system, the decimal module is ~180x slower. Using Python 3.5, the decimal module is in only ~2.5x slower.

If you care about decimal performance, Python 3 is much faster.

Java, 80 79 59 57 bytes

s->s.compareTo(new java.math.BigDecimal(new Float(s))+"")

Outputs a negative integer if the internal floating point value is larger; 0 if they're the same; and a positive integer if the floating point is smaller.

Try it online.

Explanation:

s->                          // Method with String parameter and integer return
  s.compareTo(               //  Compare the input to (resulting in neg/0/pos):
   new java.math.BigDecimal( //   Create a BigDecimal, with value:
    new Float(s))            //    The (32-bit) floating point number of the input
   +"")                      //   Convert that BigDecimal to a String

Minor note: I've used Float (which is 32 bits) and therefore holds slightly different values than in the challenge description. If I would change it to Double (which is 64 bits) the values would be the same as the challenge description. This difference can for certain inputs also result in different outputs (e.g. the "0.09" is 0.0900000035762786865234375 as float, resulting in -23, but 0.0899999999999999966693309261245303787291049957275390625 as double, resulting in 1). The overall functionality would still be the same, though:
Try it online.