Adicionado raw_id_fields.

sigi/apps/servicos/admin.py

@@ -7,6 +7,7 @@ from sigi.apps.servicos.models import Servico
 class ContatosInline(generic.GenericTabularInline):
     model = Contato
     extra = 2
+    raw_id_fields = ('municipio',)
     verbose_name = 'colaborador Interlegis'
     verbose_name_plural = 'colaboradores Interlegis'
 
@@ -15,6 +16,7 @@ class ServicoAdmin(admin.ModelAdmin):
     inlines = (ContatosInline,)
     list_display = ('id', 'titulo', 'tipo', 'convenio', 'situacao')
     list_filter  = ('tipo','situacao', 'avaliacao')
+    raw_id_fields = ('convenio',)
     search_fields = ('titulo', 'tipo', 'descricao')
 
 admin.site.register(Servico, ServicoAdmin)