Import large package lazily to speed up startup (#5636)

* Import large package lazily to speed up startup

* Make all jsonschema imports lazy

src/pretix/control/views/dashboards.py

@@ -60,7 +60,6 @@ from pretix.base.models import (
 )
 from pretix.base.services.quotas import QuotaAvailability
 from pretix.base.timeline import timeline_for_event
-from pretix.control.forms.event import CommentForm
 from pretix.control.signals import (
     event_dashboard_widgets, user_dashboard_widgets,
 )
@@ -341,6 +340,8 @@ def welcome_wizard_widget(sender, **kwargs):
 
 
 def event_index(request, organizer, event):
+    from pretix.control.forms.event import CommentForm
+
     subevent = None
     if request.GET.get("subevent", "") != "" and request.event.has_subevents:
         i = request.GET.get("subevent", "")

src/pretix/control/views/event.py

@@ -98,7 +98,6 @@ from pretix.control.views.mailsetup import MailSettingsSetupView
 from pretix.control.views.user import RecentAuthenticationRequiredMixin
 from pretix.helpers.database import rolledback_transaction
 from pretix.multidomain.urlreverse import build_absolute_uri, get_event_domain
-from pretix.plugins.stripe.payment import StripeSettingsHolder
 from pretix.presale.views.widget import (
     version_default as widget_version_default,
 )
@@ -1666,6 +1665,8 @@ class QuickSetupView(FormView):
                                          'or take your event live to start selling!'))
 
         if form.cleaned_data.get('payment_stripe__enabled', False):
+            from pretix.plugins.stripe.payment import StripeSettingsHolder
+
             self.request.session['payment_stripe_oauth_enable'] = True
             return redirect(StripeSettingsHolder(self.request.event).get_connect_url(self.request))