IDLE: Reduce number and time for user process imports

GitHub fields:

assignee = 'https://github.com/terryjreedy'
closed_at = None
created_at = <Date 2016-07-16.23:19:16.232>
labels = ['expert-IDLE', 'type-feature', '3.7']
title = 'IDLE: Reduce number and time for user process imports'
updated_at = <Date 2020-07-12.09:17:16.221>
user = 'https://github.com/terryjreedy'

bugs.python.org fields:

activity = <Date 2020-07-12.09:17:16.221>
actor = 'cheryl.sabella'
assignee = 'terry.reedy'
closed = False
closed_date = None
closer = None
components = ['IDLE']
creation = <Date 2016-07-16.23:19:16.232>
creator = 'terry.reedy'
dependencies = []
files = ['43759']
hgrepos = []
issue_num = 27534
keywords = ['patch']
message_count = 6.0
messages = ['270592', '295460', '295470', '295471', '341654', '373550']
nosy_count = 3.0
nosy_names = ['terry.reedy', 'cheryl.sabella', 'anthonypjshaw']
pr_nums = ['2011']
priority = 'normal'
resolution = None
stage = 'needs patch'
status = 'open'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue27534'
versions = ['Python 3.6', 'Python 3.7']