Metronome mark interfers with note spacing

[René Brandenburger]

Hello,

is there a way to get the metronome mark not to interfere with note
spacing?
if I remove the metronome mark in the following snippet, all eight notes
are spaced evenly, with the metronome mark, the space between the first
and the second note is much larger.

thanks

rene

8< --- SNIPPET --- >8
\version "2.11.33"
\include "italiano.ly"
\paper {
  ragged-right = ##t
 }
\relative do' {
  \time 2/4
  \tempo 4 = 100
  \key re \major
  \clef treble
  la'8 la si si |
}
8< --- SNIPPET --- >8