diff --git a/swh/scanner/cli.py b/swh/scanner/cli.py
index f265421..7fde5a8 100644
--- a/swh/scanner/cli.py
+++ b/swh/scanner/cli.py
@@ -1,113 +1,116 @@
 # Copyright (C) 2020  The Software Heritage developers
 # See the AUTHORS file at the top-level directory of this distribution
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
 
+# WARNING: do not import unnecessary things here to keep cli startup time under
+# control
 import click
-import asyncio
-import glob
-import re
-import fnmatch
 from pathlib import PosixPath
 from typing import Tuple
 
-from .scanner import run
-from .model import Tree
-from .plot import generate_sunburst
-from .dashboard.dashboard import run_app
-from .exceptions import InvalidDirectoryPath
-
 from swh.core.cli import CONTEXT_SETTINGS
 
 
 @click.group(name="scanner", context_settings=CONTEXT_SETTINGS)
 @click.pass_context
 def scanner(ctx):
     """Software Heritage Scanner tools."""
     pass
 
 
 def parse_url(url):
     if not url.startswith("https://"):
         url = "https://" + url
     if not url.endswith("/"):
         url += "/"
     return url
 
 
 def extract_regex_objs(root_path: PosixPath, patterns: Tuple[str]) -> object:
     """Generates a regex object for each pattern given in input and checks if
        the path is a subdirectory or relative to the root path.
 
        Yields:
           an SRE_Pattern object
     """
+    import glob
+    import fnmatch
+    import re
+    from .exceptions import InvalidDirectoryPath
+
     for pattern in patterns:
         for path in glob.glob(pattern):
             dirpath = PosixPath(path)
             if root_path not in dirpath.parents:
                 error_msg = (
                     f'The path "{dirpath}" is not a subdirectory or relative '
                     f'to the root directory path: "{root_path}"'
                 )
                 raise InvalidDirectoryPath(error_msg)
 
         if glob.glob(pattern):
             regex = fnmatch.translate(str(PosixPath(pattern)))
             yield re.compile(regex)
 
 
 @scanner.command(name="scan")
 @click.argument("root_path", required=True, type=click.Path(exists=True))
 @click.option(
     "-u",
     "--api-url",
     default="https://archive.softwareheritage.org/api/1",
     metavar="API_URL",
     show_default=True,
     help="url for the api request",
 )
 @click.option(
     "--exclude",
     "-x",
     "patterns",
     metavar="PATTERN",
     multiple=True,
     help="recursively exclude a specific pattern",
 )
 @click.option(
     "-f",
     "--format",
     type=click.Choice(["text", "json", "ndjson", "sunburst"], case_sensitive=False),
     default="text",
     help="select the output format",
 )
 @click.option(
     "-i", "--interactive", is_flag=True, help="show the result in a dashboard"
 )
 @click.pass_context
 def scan(ctx, root_path, api_url, patterns, format, interactive):
     """Scan a source code project to discover files and directories already
     present in the archive"""
+    import asyncio
+    from .scanner import run
+    from .model import Tree
+    from .plot import generate_sunburst
+    from .dashboard.dashboard import run_app
+
     sre_patterns = set()
     if patterns:
         sre_patterns = {
             reg_obj for reg_obj in extract_regex_objs(PosixPath(root_path), patterns)
         }
 
     api_url = parse_url(api_url)
     source_tree = Tree(PosixPath(root_path))
     loop = asyncio.get_event_loop()
     loop.run_until_complete(run(root_path, api_url, source_tree, sre_patterns))
 
     if interactive:
         root = PosixPath(root_path)
         directories = source_tree.getDirectoriesInfo(root)
         figure = generate_sunburst(directories, root)
         run_app(figure, source_tree)
     else:
         source_tree.show(format)
 
 
 if __name__ == "__main__":
     scan()